Category: Serve statistics

All Hail the Iga Swiatek … Serve?

Iga Swiatek at the 2023 US Open. Credit: Hameltion

There are a million things to praise about Iga Swiatek’s tennis these days. This puts commentators in a quandary, because her matches are often so short that there isn’t time to list them all. She is world-class at nearly every aspect of the game.

If there is an exception, it is her serve. While it is not a liability, it doesn’t appear to stand out as a weapon, and Swiatek continues to make technical tweaks to improve it. She doesn’t dominate first-serve points the way that Qinwen Zheng or Elena Rybakina does; she doesn’t pile up aces like Rybakina, Karolina Pliskova, or Aryna Sabalenka. The longer a point lasts, the more time she has to take control, so who needs a standout first strike?

A look at the bigger picture, though, tells us that Iga’s serve is just fine. She was broken just five times in six matches en route to her second Indian Wells title. In the last 52 weeks, she has held 81.6% of her service games, best on tour.

To quote myself when Alex Gruskin threw that stat at me a couple of weeks ago: Wait, WHAT?!

Here’s the top ten since Miami 2023:

Player              Hold%  
Iga Swiatek         81.6%  
Aryna Sabalenka     79.4%  
Elena Rybakina      78.5%  
Caroline Garcia     76.4%  
Madison Keys        76.4%  
Petra Kvitova       75.8%  
Katie Boulter       74.3%  
Qinwen Zheng        73.2%  
Liudmila Samsonova  73.1%  
Maria Sakkari       73.0%

I can already hear everybody sputtering out their “yeah but” explanations, and we’ll get to some of them in a moment. First, though, we need to acknowledge just how elite this is. Sabalenka held at 80.8% last year, her best campaign so far. In 2015, when Serena Williams went 53-6 and won three majors, she held 80.9% of service games. Ash Barty peaked at 80.1%. Pliskova has twice cracked 79% for a full season, but never 80%. Same for Kvitova.

WTA match stats are sparse before the mid-2010s, so I don’t have numbers for Navratilova, Graf, Davenport, Venus Williams, and the rest. (Navratilova won 75% of total games in 1983, so… wow.) Suffice it to say, hold percentages that start with an eight are the province of all-time serving greats. Iga has muscled her way into that group.

The all-rounder

The simplest explanation of Swiatek’s serve stats is that she wins a lot of all kinds of points. As long as she doesn’t double fault, she’s in a rally, and she doesn’t lose many rallies.

This is true, sort of. In the last 52 weeks, Iga has won almost half of her return points, good for a break percentage of 49.5%. That leads the tour as well, granting her a spot in the hyper-exclusive Top One Club.

The average player in the WTA top 50 has a hold percentage about 33 points higher than her break percentage. Iga’s difference of 32 points, then, is not far from the norm. Despite winning so many service points, she is an entirely different sort of player than Rybakina (43 point gap) or Caroline Garcia (55 [!] point gap). Swiatek tacks an average serve onto a game that is otherwise outlandish.

On the other hand, it’s easy to underrate average. Most players who are extremely good at one thing are lucky if the rest of their game can pull enough weight to keep them on tour. The biggest servers are often indifferent (at best) on return; the best baseline players are rarely blessed with world-beating serves. Here are the current top ten returners among the top 50 (plus #52 Sara Sorribes Tormo), shown with their hold percentages and the differences between their serve and return results:

Player               Break%  Hold%   Diff  
Iga Swiatek           49.5%  81.6%  32.1%  
Lesia Tsurenko        48.1%  56.4%   8.3%  
Sara Sorribes Tormo   47.5%  58.4%  10.9%  
Clara Burel           45.4%  61.3%  15.9%  
Coco Gauff            44.7%  71.2%  26.5%  
Daria Kasatkina       44.5%  62.4%  17.9%  
Marketa Vondrousova   44.0%  68.7%  24.7%  
Jessica Pegula        43.1%  72.0%  28.9%  
Elise Mertens         41.0%  65.2%  24.2%  
Katerina Siniakova    40.2%  61.3%  21.1%  
Ons Jabeur            40.1%  67.0%  26.9%

If we approximate “serve-specific skill” as the difference between hold and break percentage, we find that the best returners are–unsurprisingly–generally weaker servers. Everyone on this list is below average in serve-specific skill. Among this group of elite returners, though, Iga is the best server. Only a few women–familiar names like Pegula and Gauff–come close.

Here is the relationship in visual form:

Iga clearly occupies a world of her own.

What works

One thing Swiatek does well is that she can hit her serve hard. At least year’s US Open, 40 different women had at least 100 first serves that landed in the box and registered on the radar gun. The top of the list are the names you’d expect: Sabalenka, Qinwen Zheng, Samsonova, Gauff, and Keys. Next up were Elise Mertens and… Iga Swiatek. Iga’s average first serve was a rounding error away from Keys’s and just 2.5 km/h slower than Gauff’s.

Speed matters, obviously. All else equal, a faster serve means more aces, more short points, and more service points won. The spin that Swiatek generates may make her first serves more difficult than the radar gun indicates, as well. When five-foot, four-inch Yulia Putintseva challenged the Iga serve at Indian Wells, she often found herself making contact at or above head level. Putintseva, I suspect, would have preferred to take on a flatter hitter like Samsonova, even if it meant handling a few more miles per hour.

Raw speed might also be underrated. When I dug into some ATP numbers to tease out the effects of speed and precision last month, I found that speed seems to matter more than accuracy. Equivalent data isn’t available for the women’s game (and the men’s data itself was exceedingly sparse), but it seems reasonable to assume that the relationship would be similar.

The relative effects of speed and precision are particularly important to Swiatek, because she hits a lot of her serves down the middle of the box. (Technically, those serves could still be “precise,” in the sense that they land close to the service line, but they won’t be as unreturnable as the equivalent deep serve close to a sideline.) Match Charting Project data tells us that the average WTAer hits 21% of their first serves down the middle. Iga comes in at 32%. Returners start the point on the back foot, even if they don’t have to move their back foot very far.

Swiatek gets away with all those down-the-middle serves, partly because she is better than her peers in general, and partly because she sacrifices less effectiveness than average by choosing a more conservative target. Here are her first-serve winning percentages by direction:

Direction   Iga W%  Tour W%  
Deuce-Wide     68%      65%  
Deuce-Body     64%      57%  
Deuce-T        74%      67%  
Ad-T           69%      64%  
Ad-Body        63%      56%  
Ad-Wide        69%      64%

(I use “down the middle” and “body” interchangeably here, because that’s how Match Charting Project logs are coded. Within tennis, the term “body serve” often refers to a narrower category of balls aimed directly at the returner. Iga hits some of those, but an awful lot of her serves–even her first serves–are neither that sort of body serve nor a delivery aimed at a corner.)

The average player gives up eight percentage points when they go down the middle. Iga sacrifices only six. It also helps to be so good in general. A winning percentage of 63% or 64% will keep you in a service game; 56% or 57% will put it much more at risk.

82%, here we come

One benefit of scoring so many points with down-the-middle serves is that it allows Swiatek to save the angles for when it matters most. It’s tough to pinpoint exactly what the key moments are for Iga, since her matches are often so lopsided. Serving at 4-all in the first set against Maria Sakkari yesterday, she built a 30-15 advantage with three first serves to the body. She served wide on the next point and down the T at 40-15. Neither one came back. She didn’t lose another game the rest of the way.

My hypothesis, based on watching her recent matches, was that this was a recurring pattern, that Iga goes to the corners more on key points and thus holds serve even more often than her serve-point success would indicate. But this is wrong, at least facing break points over the last 52 weeks. Since Miami last year, she has won 64.6% of serve points, but only 60.6% against break point. Most women save break points less often than they win other serve points, because break points tend to be generated by stronger returners. But a margin of two percentage points is typical. Iga’s four-point gap is not.

In fact, Swiatek was dreadful facing break point last year. A few years ago I built a metric to measure each player’s success rate at break point, comparing their break points saved to the number of points they’d be expected to win based on the other serve points played in those matches. By Break Points Over Expected (BPOE) in 2023, Iga was dead last among tour regulars. She faced 311 break points, and if she had served as well on those points as she did in the rest of those matches, she would have saved 184 of them. Instead, she saved 165, a difference of -19. No other top player had a negative result worse than -5.

Fortunately for the Polish star, this is the kind of clutch (or anti-clutch) performance that tends not to persist. Either it’s bad luck, or the choking turns out to be temporary. And indeed, in 2024, Swiatek has turned things around. She has saved 76 of 109 break points faced instead of the expected number of 66. She probably won’t sustain that level of break point overperformance, but even a neutral score would further improve her tour-leading hold percentage. If she could prove out my hypothesis and win more break points than expected by saving her best serves for those moments, she would head further into untouchable territory.

No one will ever mistake the Swiatek serve for the cannon of Sabalenka or Rybakina. But Iga’s overall game means she wins more points than the heavier hitters. Her serve doesn’t have to be great, it just needs to stick around tour average. She has achieved that, and–pity her poor opponents–there is room for her to improve even more.

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Can Sebastian Baez Find Success on Hard Courts?

Sebastian Baez in Cordoba last month. Credit: jmmuguerza

Sebastian Baez is a marvel. In an era dominated by tall, all-court sluggers, the five-foot, seven-inch Argentinian has carved out a place on the circuit as a throwback clay-court specialist. Just a couple of months past his 23rd birthday, he has already won six tour-level titles and reached a new career-best ranking of 19th on the ATP computer.

The obvious comparison is Diego Schwartzman, another Argentinian on the small side who won titles and reached a French Open semi-final by grinding out victories and swinging above his weight. Schwartzman eventually cracked the top ten, but when he was Baez’s age, such a milestone looked extremely unlikely. When he turned 23, he stood outside the top 60, heading back to South America for another cycle through the continent’s late-season Challenger swing. He wouldn’t reach the top 20 for another two and half years.

If we assume Baez continues to improve throughout his mid-20s in the same way that Schwartzman did, a single-digit ranking seems achievable. He’s already 11th on tour in clay court Elo. Only a few players ahead of him on the official ranking table are younger.

The main stumbling block is the natural ceiling on dirtballers. There are far more ranking points available on hard courts than on clay, and one of the prime opportunities on the Argentinian’s favorite surface, in Madrid, plays fast because of its altitude. (Baez has competed there only once, losing in the second round last year to another sterling clay-courter, Stefanos Tsitsipas. Schwartzman never won more than two matches there, either.) For Schwartzman to gain a top-ten place, he needed more than a Roland Garros semi-final: He had recently reached indoor finals in Vienna and Cologne, and he was 14 months removed from defeating Taylor Fritz for a hard-court title in Los Cabos. Diego’s magic somehow worked on all surfaces. Even in a year when he posted outstanding results on clay, that was his only route to a single-digit ranking.

Baez owns one hard-court championship, from last year’s US Open warmup in Winston-Salem. But apart from that week, his story diverges from Schwartzman’s, with a career record on the surface of just 17-33. He has never won two completed matches at any other tour-level hard-court event. (His two third round appearances at majors were aided by retirements.) The Argentinian can be a star and a national hero without all-surface success, but surely he wants more. Can he achieve it?

Surface and speed

When I wrote about surface sensitivity a couple of weeks ago, Baez didn’t stand out as an extreme. Tsitsipas and Lorenzo Musetti were the men whose results were most dependent on slow courts. The numbers showed that Baez does better with a slower bounce, but the effect is less than half of what it is for Tsitsipas. The 23-year-old is more closely comparable in this department to Daniil Medvedev, who doesn’t like to play on clay–or eat it.

However, that analysis left out one major factor. I simply rated tournaments by the degree to which they helped servers end points quickly, regardless of surface. Indian Wells, on hard courts, came out as just barely speedier than Rome and slower than Madrid. Miami and the US Open were roughly equivalent to the Caja Magica as well.

Intuitively, there is more than one dimension to player preferences. Some men might just want more time to prepare, as could be the case with Tsitsipas and his one-handed backhand. But others–Baez among them–are much more comfortable on a certain type of surface, because of the type of bounce, the footing, or both. When we reduce surface type and speed to one variable, Baez and Medvedev come out equal. When we separate type from speed, they look very different.

This scatterplot shows 56 players on the two dimensions:

(The units are regression coefficients and essentially meaningless out of context. They do, however, show direction and magnitude of each player’s preferences.)

Among players with at least 100 tour-level matches since 2021, Baez ranks third in the degree of his preference for clay courts, behind Albert Ramos and roughly tied with Alexander Zverev. Once surface type is controlled for, he prefers faster courts. Santiago, where he won the title last week, is one of the quicker clay courts on the circuit, giving servers as many quick points as Wimbledon (really!). Rio de Janeiro, the site of his triumph the week before, is also faster than the average dirt, rating about the same as Indian Wells.

Medvedev is the exact opposite. Only Adrian Mannarino has a stronger demonstrated yen for hard courts. Once his choice of surface is secure, though, the Russian wants it as slow as possible. Only a few players (including Musetti and another slow-hard-specialist, Alex de Minaur) are so extreme.

Schwartzman–the model for a potential all-court Baez–prefers clay, and he likes all of his courts slow. His performance is even more speed-dependent than Medvedev’s, but his surface type preference isn’t nearly as strong as that of his younger countryman.

This is all rather abstract, and to some degree, it’s just a fancy way of saying that Baez struggles on hard courts. Let’s make things more concrete by looking at what happens when the Argentinian shifts to the tour’s more popular surface.

Translations

Hard-court tennis is more serve-dominated than the clay-cout variety. The typical tour regular wins, on average, 3% more service points on hard than on clay: 4% more first-serve points and 1% more second-serve points. They win 7% fewer return points. (That sounds like a paradox, since the serve and return numbers are different. The catch comes from specifying “tour regulars”–part-timers on hard courts have bigger serves than their equivalents at clay events.)

Here are the player-specific numbers for each man in the top 20 (except for Ben Shelton, who hasn’t played much on clay). The figures are ratios of each hard-court metric to the corresponding clay-court metric–serve points won, first-serve points won, and return points won–so the higher the number, the bigger the difference in favor of hard courts.

Player               SPW  1st SPW   RPW  
Ugo Humbert         1.10     1.08  0.95  
Novak Djokovic      1.09     1.11  0.91  
Alex de Minaur      1.08     1.08  0.99  
Daniil Medvedev     1.06     1.07  0.98  
Jannik Sinner       1.06     1.08  0.95  
Tommy Paul          1.06     1.08  1.08  
Grigor Dimitrov     1.06     1.04  0.95  
Holger Rune         1.05     1.06  0.92  
Taylor Fritz        1.05     1.09  0.93    
Alexander Zverev    1.05     1.03  0.89

Player               SPW  1st SPW   RPW  
Alexander Bublik    1.05     1.04  1.04  
Karen Khachanov     1.05     1.09  0.96  
Andrey Rublev       1.05     1.05  0.94  
Hubert Hurkacz      1.04     1.02  1.00  
Frances Tiafoe      1.03     1.05  0.95  
- ATP Regular -     1.03     1.04  0.93  
Carlos Alcaraz      1.02     1.02  0.92  
Stefanos Tsitsipas  1.02     1.03  0.89  
Casper Ruud         1.01     1.04  0.91  
Sebastian Baez      0.94     0.96  0.85

Baez is… different. Everyone in the top 20 wins more serve points on hard courts than on clay except for him. Only a few other men on tour have the same “backwards” split, and only Federico Coria is close to Baez in the degree of his weaker hard-court service performance. What costs the Argentinian even more is how his return numbers suffer away from clay. Almost everyone wins fewer return points on hard, but Baez takes the cake here too.

Perhaps needless to say, there’s no way that this can work. Baez wins about 62% of service points on clay, a respectable number and an impressive one for someone his size, but still below the average of a top-50 player on the surface. To win even fewer on hard suggests that he would struggle even at Challenger events. At Winston-Salem last August, Baez won 63.5% of his serve points and over 43% on return. That’s a combination that will win matches; he just hasn’t provided any evidence that he can pull it off once he crosses back out of North Carolina.

Growth rate

The one reason for optimism is that Baez is young, inexperienced on surfaces other than clay. Like Schwartzman, he grew up playing on dirt, and he rose through the rankings by winning South American Challengers, then picking up victories on the continent’s Golden Swing. Maybe there’s a necessary transition period?

Here are the same ratios as above, now by season for our two Argentinian heroes:

Player  Year   SPW  1st SPW   RPW  
Diego   2015  1.01     0.99  1.01  
Diego   2016  1.04     1.07  0.94  
Diego   2017  1.08     1.09  0.91  
Diego   2018  1.03     1.03  0.89  
Diego   2019  1.08     1.09  0.94  
Diego   2020  1.03     1.03  0.85  
Diego   2021  1.02     1.03  0.95  
Diego   2022  1.01     1.04  0.89  
Diego   2023  1.09     1.08  0.88  
                                   
Player  Year   SPW  1st SPW   RPW  
Baez    2022  0.91     0.94  0.82  
Baez    2023  0.96     0.99  0.88

Baez did close the gap between his hard-court and clay-court performances in his second year on tour. But he still shows a more marked surface preference than Schwartzman ever did. As soon as Diego arrived on tour, he was able to win more service points on hard courts–roughly the same ratio as the typical tour regular. Baez isn’t even close. Schwartzman had to retool his game to succeed on hard courts, and Baez will need to do so even more.

The 23-year-old truly is a throwback, an undersized grinder who spins in his serves, plays defense, and constructs points. It’s a joy to watch, and the package makes him one of the best players on tour for the 14 weeks or so each year when there are top-level clay events on offer. It doesn’t, however, work so well when there’s no dirt to kick out of his cleats. Fortunately Baez is young, and he has many years left to figure it out. He’ll need to.

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Alex de Minaur’s Adequate Inaccuracy

Alex de Minaur at the 2024 Australian Open. (Getty Images: Julian Finney)

Last week, Tennis Insights posted a graphic showing the average first serve speed and accuracy–distance from the nearest line–for the ATP top 20. There’s a ton of fascinating data packed into one image.

Hubert Hurkacz is fast and accurate, Novak Djokovic is nearly as precise, and Adrian Mannarino defies logic as always. The most noteworthy outlier here, especially just after his run to the Rotterdam final, was Alex de Minaur. The Australian gets plenty of pop on his first serve, hitting them faster than tour average, if slower than most of the other men in the top 20. This comes at a cost, though. As one of the shortest guys among the elite, he doesn’t hit the lines. He’s by far the least accurate server in this group:

Via @tennis_insights

Precision is great: It’s certainly working for Hurkacz and Djokovic. But everything is a tradeoff. Any pro player could hit more lines if there was no reason to serve hard. Or vice versa: If the goal was simply to light up the radar gun, these guys could add miles per hour by aiming at the middle of the box. Standing a modest six feet tall, De Minaur is even more constrained than his typical peer. No technical tweak is likely to move him into Hurkacz territory. He might make small improvements or swap some speed for more accuracy.

Small gains would be enough, too. De Minaur wins fewer first-serve points than the average top-50 player, but in the last 52 weeks, he has outpaced Carlos Alcaraz, Holger Rune, and Casper Ruud. He trails Alexander Zverev by about one percentage point. This isn’t Sebastian Baez (or even Mannarino) we’re talking about. Whatever the cost of de Minaur’s inaccuracy, he’s able to overcome it. It’s just a matter of what gains he could reap by making returners work a bit harder.

Here’s the question, then: How much does accuracy matter?

Speed first

For this group of players over the last 52 weeks, speed is by far the most important factor in first-serve success. Speed alone–ignoring accuracy or anything else–explains 72% of the variation in first-serve points won. Accuracy alone accounts for 43%. (The players who are good at one thing are often good at others, so most of those 72% and 43% overlap.) 43% might sound like a lot, but isn’t that far ahead of something as fundamental as height, which explains 33% of the variation.

Surprisingly, precision is even less critical when it comes to unreturnable first serves. Using unreturned serve counts from Match Charting Project data, accuracy explains just 30% of the variation in point-ending first serves, less than we could predict from height alone. (Speed alone explains 60% of the variation in unreturned serves.) I would have expected that accuracy would play a big part in aces and other unreturned serves, since a ball close to the line is that much harder to get a racket on. But while precision may increase the odds of any individual serve going untouched, average precision isn’t associated with untouchable serving.

The story is the same for any metric associated with first-serve success. Speed matters most. There’s immense overlap between the factors I’ve discussed: Taller players find it easier to hit the corners, and all else equal, they take less of a risk by hitting bigger. There is probably some value of height that isn’t captured by speed or accuracy, such as the ability to put more spin on the ball, but the main benefit shows up on the radar gun.

To tease out the impact of each variable, I ran a regression that predicts first-serve points won based on speed, accuracy, and height. The results should be taken with an enormous grain of salt, since we’re looking at just 20 players, some of them the game’s most outrageous outliers. Still, the findings are plausible:

  • Speed: Each additional mile per hour translates to an improvement of 0.43 percentage points in first-serve points won. (1 kph: +0.27 first-serve points won)
  • Accuracy: Decreasing distance from the line by 1 cm results in an improvement of 0.2 percentage points in first-serve points won.
  • Height: At least for these twenty players, the value of height is entirely captured by speed and accuracy. The margin of error for the height coefficient spans both positive and negative values. It is unlikely that height is a negative, though I suppose it’s possible, if speed and accuracy capture the height advantage on the serve itself, and height is a handicap on points that develop into rallies. Either way, the impact is minor, if it exists at all.

Approximately, then, one additional mile per hour is worth the same as two centimeters of accuracy. The height of the graph–110 to 130 mph–represents a variation of nearly 9 percentage points of first-serve points won. The width–70 to 52cm–represents a range of 3.6 percentage points. Broadly speaking, speed remains more important than accuracy, though a particular player might find it easier to improve precision than power.

Just one example of what the numbers are telling us: De Minaur has won 72.8% of his first-serve points over the last year, compared to the top-ten average of 75.3%. If this model were to hold true–a big if, as we’ll discuss shortly–that’s a gap he could close by improving precision by about 12 cm, to a tick better than tour average.

Drowning in caveats

For every question we answer, we’re rewarded with ten more questions.

I’m most interested in the choices that individual players could conceivably make, and the analysis so far offers only hints to that end. For this group of servers, we can say that a player who serves faster will win more points than his slower-serving peers. But we don’t know whether a specific player, if he was able to juice his serve by a mile or two per hour, would enjoy the same benefits. Hitting harder, or placing the ball more accuracy, is better, but by how much?

(I dug into the speed question way back in 2011 and found that one additional mile per hour–for the same player–was worth 0.2 percentage points. More recently, I found that for Serena Williams, an additional mile per hour was worth 0.5 percentage points. One of these days I’ll revisit the initial study with the benefit of many more years of data and perhaps a bit more wisdom.)

De Minaur was unusually precise in Rotterdam. Another Tennis Insights graphic indicates that his accuracy improved to about 55 cm for the week, an enormous gain of 15 cm from his usual rate, even more remarkable because his average speed was a bit quicker as well. (Playing indoors probably helped.) The model suggests that 15 cm is worth three percentage points. His boost of two miles per hour should have been worth nearly one more percentage point itself. Yet he won “only” 73.9% of his first-serve points–about one percentage point better than his non-Rotterdam average.

It’s just one week, so it isn’t worth fretting too much over the discrepancy. Still, it illustrates the value of the data we don’t have. (By “we,” I mean outsiders relying on public information. The data exists.) If we knew de Minaur’s accuracy and speed for every match, we could figure out their value to him specifically. Perhaps an uptick of one mile per hour is worth 0.43 percentage points only if you start serving like the players who serve faster–guys who are generally taller and can put more slice or kick on the ball. Those weapons aren’t available to the Aussie, so a marginal mile per hour may be less valuable. For him, accuracy might have a bigger payoff–relative to speed–than it does for other players. We just don’t know.

Sill, we’ve extracted a bit of understanding from the data. We’ve seen that accuracy translates into more first-serve points won, and we have a general idea of how many. De Minaur showed himself capable of hitting the lines as precisely as Andrey Rublev or Grigor Dimitrov, at least under a roof for one week. Just half that improvement, if he could sustain it–even if he didn’t get the full gains predicted by the model–would shore up a mediocre part of his game and lay the groundwork for a longer stay in the top ten.

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Surface Sensitivity and Ugo Humbert’s Serve

Ugo Humbert in 2023. Credit: Hameltion

Let’s start off with a couple of puzzles. I realize they aren’t the sort of things that keep most of you up at night, but they were odd enough to drive me to a flurry of coding, data analysis, and now blog writing.

On Wednesday, Ugo Humbert lost his first-round match in Rotterdam to Emil Ruusuvuori. It marked an unceremonious end to a hot streak for Humbert: He not only won the title in Marseille last week–launching himself into the Elo top ten–but he strung together 31 consecutive holds. 1,000 kilometers north, on a different indoor hard court, he got broken twice by a man ranked outside the top 50.

That’s the first puzzle: Why did the Frenchman lose? Again, it’s not that odd, as my Elo ratings gave Ruusuvuori a one-in-three shot to pull the upset. But it’s a match that Humbert should have won.

Head-scratcher number two: Why does Humbert always lose to Ruusuvuori? Wednesday’s decision marked their fifth meeting, and the Finn is undefeated. While the outcome is always close–Rotterdam was their fourth deciding set, and the other match went to two tiebreaks–the results are starting to get boring. Ruusuvuori is a solid player, and he is consistently able to blunt the Frenchman’s serve. But five in a row?

The answer to both mysteries is the same, and it’s more satisfying than I expected. Rotterdam is unusually slow for a hard court, especially indoors. Like most (or perhaps all) of the previous Humbert-Ruusuvuori venues, it plays slower than tour average. Just as important, Humbert’s game is unusually sensitive to surface speed. While that isn’t always true of big servers, he stands out as a fast-court specialist. We couldn’t have confidently predicted a Finnish upset, but we could have guessed that the Marseille champion would find this week’s tournament tougher going.

Rotterdam, it’s slow

The last time I published surface speed numbers, in late 2019, Rotterdam rated as the slowest indoor hard court on tour. Adjusting for the mix of players at the event, there were 10% fewer aces at the tournament than expected. It was a sharp decline from 2017 and 2018, when the venue sported more typically speedy indoor conditions.

Since then, the results have remained similar. Last year, the rate was 5% lower than expected, roughly tied with Stockholm as the slowest indoor surface on tour. Marseille, by contrast, gave players 12% more aces than usual.

There are limitations to using aces as a proxy for surface speed; I use aces because it’s the most relevant data that is widely available. Still, while you can quibble about the methodology or about a specific tournament’s place on the list, the overall rank order seems about right. Aces–adjusted for each event’s field–tell you much of the story.

With a growing mass of Match Charting Project data, we can do a little better. We have shot-by-shot logs for over one thousand matches since 2021. To compare conditions, I used my Serve Impact metric, which estimates how many points a player wins, directly or indirectly, because of his serve. It counts aces, other unreturned serves, and a fraction of the service points that take longer to decide. Depending on your motivation in measuring court speed, this isn’t perfect either: It doesn’t directly tell you anything about bounce height, for instance. But if you want to know what sort of players a tournament favors, Serve Impact gets you close.

By this more sophisticated metric, Rotterdam is… still slow. The venue takes away 4% of the points a player typically earns from his serve. Marseille and Montpellier each swing 7% in the other direction, Stockholm and Vienna provide a modest 3% boost, and Basel adds 8% to the server’s punch. With the exception of the short-lived tour stop in Gijon, Rotterdam has been the slowest indoor hard court of the 2020s. Even the clay in Lyon plays faster.

Here are the Serve Impact adjustments for the tournaments best represented in the dataset. Higher numbers mean faster conditions with more points decided based on the serve:

Tournament            ServeImpact  
Stuttgart                    1.29  
NextGen Finals               1.20  
Tour Finals                  1.16  
Wimbledon                    1.11  
Shanghai Masters             1.11  
Halle                        1.10  
Queen's Club                 1.08  
Basel                        1.08  
Washington                   1.08  
Dubai                        1.07  
                                   
Tournament            ServeImpact  
Antwerp                      1.05  
Gstaad                       1.05  
Australian Open              1.04  
Davis Cup Finals             1.04  
Cincinnati Masters           1.04  
Paris Masters                1.03  
Vienna                       1.03  
Miami Masters                1.02  
Madrid Masters               1.01  
US Open                      1.01  
                                   
Tournament            ServeImpact  
Canada Masters               1.00  
Rotterdam                    0.96  
Indian Wells Masters         0.95  
Rome Masters                 0.92  
Acapulco                     0.87  
Barcelona                    0.87  
Roland Garros                0.83  
Monte Carlo Masters          0.83

Average Serve Impact is around 34%, so the 4% hit in Rotterdam knocks that down to about 32.6%. Humbert has an above-average serve, so the slow-court penalty is greater still. He isn’t going to win any awards for rallying prowess, especially against someone as sturdy as Ruusuvuori, so the points that he doesn’t secure with his serve will disproportionately go against him.

The first three meetings in the Humbert-Ruusuvuori head-to-head were on clay, at Roland Garros, Madrid, and Rome. The fourth came on grass, at ‘s-Hertogenbosch. It rates a bit faster from 2021-23 than Halle or Queen’s Club by the Serve Impact metric, though it rated as the slowest grass court on tour last year by my older ace-rate algorithm. Maybe it was less server-friendly in 2023, just in time for Humbert to be flummoxed once again.

Surface sensitivity

We tend to take for granted that players are suited to conditions in predictable ways. Big servers like fast surfaces, right? Broadly speaking, yes, but it’s not a hard-and-fast rule. Bounce height makes a difference, footwork matters, and some players are just more comfortable on some surfaces than others.

Armed with surface speed ratings, this is something we can test. If a player is particularly sensitive to conditions, each tournament’s Serve Impact rating should have a predictable influence on his match outcomes. I tried that for all tour regulars, controlling for player strength by using overall Elo ratings at the time of each match.

The resulting numbers are an abstraction on top of an abstraction, so they’re a bit difficult to get your head around. I’ve tried to simplify matters by rendering them in terms of Elo points. A player who is very sensitive to surface and does better on hard courts is, effectively, a better player in faster conditions. The ‘Sensitivity’ numbers given here are the benefit–denominated in Elo points–of each single percentage point that a surface is faster than average. For players who like it slow, negative numbers express the same idea, the Elo-point advantage of a one-percentage-point slowdown.

Here is the list of all players with at least 100 tour-level matches since 2021, plus Rafael Nadal:

Player                       Sensitivity  
Tallon Griekspoor                   11.1  
Ugo Humbert                          9.5  
Richard Gasquet                      9.1  
Novak Djokovic                       8.7  
Adrian Mannarino                     7.9  
Sebastian Korda                      4.9  
Jordan Thompson                      4.3  
Matteo Berrettini                    4.0  
Aslan Karatsev                       3.6  
Tommy Paul                           3.4  
Marcos Giron                         2.9  
Marton Fucsovics                     2.9  
Marin Cilic                          2.6  
Felix Auger-Aliassime                2.1  
Hubert Hurkacz                       1.7  
                                          
Player                       Sensitivity  
Frances Tiafoe                       1.6  
Carlos Alcaraz                       1.4  
Emil Ruusuvuori                      1.3  
Brandon Nakashima                    1.3  
Cristian Garin                       0.6  
Alexander Zverev                     0.5  
Alexander Bublik                     0.5  
Ilya Ivashka                         0.0  
Arthur Rinderknech                  -0.1  
Taylor Fritz                        -0.3  
Jan Lennard Struff                  -0.3  
Lorenzo Sonego                      -0.4  
Mackenzie Mcdonald                  -0.5  
Andy Murray                         -0.9  
Grigor Dimitrov                     -1.1  
                                          
Player                       Sensitivity  
Roberto Bautista Agut               -1.2  
Alex de Minaur                      -1.2  
Karen Khachanov                     -1.4  
Jannik Sinner                       -1.4  
Yoshihito Nishioka                  -1.5  
Miomir Kecmanovic                   -1.9  
Andrey Rublev                       -2.2  
Daniel Evans                        -2.2  
Cameron Norrie                      -2.5  
Holger Rune                         -2.9  
Roberto Carballes Baena             -3.0  
Botic van de Zandschulp             -3.1  
Daniil Medvedev                     -3.4  
Denis Shapovalov                    -3.5  
Sebastian Baez                      -3.7  
                                          
Player                       Sensitivity  
Laslo Djere                         -4.1  
Dusan Lajovic                       -4.1  
Pablo Carreno Busta                 -4.4  
Jaume Munar                         -4.6  
Fabio Fognini                       -4.8  
Nikoloz Basilashvili                -4.9  
Casper Ruud                         -5.0  
Diego Schwartzman                   -5.4  
Francisco Cerundolo                 -5.9  
Alexei Popyrin                      -6.4  
Albert Ramos                        -6.8  
Rafael Nadal                        -9.9  
Alejandro Davidovich Fokina        -10.1  
Stefanos Tsitsipas                 -10.2  
Lorenzo Musetti                    -11.2

There’s Ugo! He’s not quite as surface sensitive as Tallon Griekspoor, but a couple of points is within the margin of error. A sensitivity rating of 9.5 means that Humbert is about 100 Elo points worse in Rotterdam than he is Marseille, as long as I’ve accurately estimated the server-friendliness of the respective playing conditions. Ruusuvuori may also like it faster, but only marginally so; he’s effectively neutral.

Keen-eyed readers may have noted that I earlier referred to “overall” Elo. I’m not using surface-specific Elo ratings here, because I don’t want to adjust for surface twice. Surface-specific ratings already capture some of this: Humbert’s hElo (for hard courts) is 120 points higher than his cElo (for clay courts), which tallies reasonably well with these more fine-grained distinctions. What hElo and cElo can’t tell us, though, is how much his (or anyone else’s) performance will vary on the same surface, depending on the conditions at each specific venue.

It’s easy to get lost in the weeds of Elo-based forecasting calculations, but it’s important to remember they are just tools to help measure a real-world phenomenon. Not every big server is equally at sea on clay; some dirtballers are less dependent on slow conditions than others. Small differences in surface speed are, for most matchups, a minor consideration. But for some players, conditions matter a lot. Ugo Humbert likes his surfaces fast, as much as almost anyone else on tour. In Rotterdam, the conditions did not cooperate.

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Elena Rybakina and the Value of Average

Also today: Ugo Humbert in the (Elo) top ten; South American Davis Cup hard courts

Elena Rybakina at the 2023 US Open. Credit: Hameltion

Never underestimate average. Establishing oneself on the top level of the pro tennis circuit is extraordinarily difficult; proving that any particular skill is average among one’s tour-level peers is even harder. Most players are better than the norm in some categories, worse in others. Anyone who can beat the middle of the pack in every department is virtually guaranteed to be a superstar.

Average is Elena Rybakina’s secret weapon. You probably didn’t know she needed one, because she has a very effective, very evident non-secret weapon: an unreadable bullet of a first serve. In the last year, over 43% of her first serves have gone unreturned. No one else on tour comes within three percentage points of that, and only five other women top 35%. On a good day, the serve can put a match out of reach nearly on its own. When she faced Aryna Sabalenka in Beijing last fall, 65% of her first serves didn’t come back. Most women barely manage to win that many first serve points, let alone decide them with one stroke.

I’ll come back to the serve in a moment, because it is so remarkable, and it would be strange to talk about Rybakina without discussing it. But what makes her a contender every week–not to mention a champion in Abu Dhabi yesterday–is the way that the rest of her game doesn’t hold her back. Among the other women who end points with more than 35% of their first serves, you’ll find a long list of weaknesses. Qinwen Zheng doesn’t put nearly enough of them in the box. Donna Vekic and Caroline Garcia struggle to break serve. Liudmila Samsonova doesn’t break much, either, and her mistakes come in excruciating, match-endangering bunches.

Lopsided player profiles make sense. Only a few people have the combination of natural gifts and discipline to develop a dominant serve. Tennis skills are correlated, but not perfectly so. Someone who serves like Vekic can often learn good-enough groundstrokes and secondary shots. But players with one standout skill are unlikely to be solid across the board. Just because someone is top ten in the world in one category, why would we expect them to rank in the top 100 by a different measure?

Rybakina has reached the top–or close, anyway–by coupling a world-class serve with a set of skills that lacks defects. (You can nitpick her footwork or technique, but none of that holds her back when it comes to winning enough points.) After we review the devastation wrought by her serve, we’ll see just how average she otherwise is, and why that wins her so many matches.

First serves first

I’ve already given you the headline number: Since this time last year, 43.4% of Rybakina’s first serves haven’t come back. That’s one percentage point better than Serena Williams’s career rate. Serena’s numbers are based on matches logged by the Match Charting Project, a non-random sample skewed toward high-profile contests against strong opponents, so I’m not ready to say outright that Rybakina is serving better than Serena. But I’m not not saying that–we’re within the margin of error.

Some back-of-the-envelope math shows what kind of gains a player can reap from the best first serve in the game. Rybakina makes about 60% of her first serves–lower than average, but probably worth the trade-off. (And improving–we’ll talk about that in a bit.) When the serve does come back, she wins about half of points, roughly typical for tour players. All told, 43% of her serve points are first-serve points won. Tack on about half of her second serve points–she wins 48% of those, better than average but not by a wide margin–and we end up with her win rate of 62.5% of serve points–fourth-best on tour.

Put another way: We combine one world-class number (unreturned first serves) with a below-average figure (first serves in), one average number (success rate when the serve come back), and one more that was slightly better than average (second-serve points won). The result is an overall success rate that trails only those of Iga Swiatek, Sabalenka, and Garcia. That, in case you ever doubted the value of an untouchable first serve, is the impact of one very good number.

The key to Rybakina’s first serve–apart from blinding speed–is its unreadability. She must lead the tour in fewest returner steps per ace, a stat I dreamed up while watching the Abu Dhabi semi-final on Saturday. Samsonova seemed to stand bolted to the ground, watching one serve after another dart past her. After one business-as-usual ace out wide, Samsonova even offered a little racket-clap of appreciation, an unusual gesture for such a routine occurrence.

In addition to the deceptiveness of a nearly identical toss and service motion, Rybakina is effective in every direction. There’s no way for an opponent to cheat to one side, hoping to get an edge on a delivery in that corner of the box. Here are Elena’s rates of unreturned first serves and total points won in each corner of the two service boxes:

Direction   Unret%  Won%  
Deuce-Wide     36%   69%  
Deuce-T        45%   75%  
Ad-T           37%   70%  
Ad-Wide        42%   74%

The average player ends points with their first serve between 20% and 25% of the time and wins 60% of their first serve points. Rybakina obliterates those numbers in every direction. If there’s a strategy to be exploited, it’s that returners ought to lean toward their forehand, because if the serve comes to their backhand, they don’t have a chance anyway.

The scariest thing for the rest of the tour is that the 24-year-old’s biggest weapon may be getting even bigger. Her 43.4% rate of unreturned first serves in the last 52 weeks compares favorably to a career clip of 38.2%. Against Samsonova on Saturday, over 41% of all serves didn’t come back, better than Rybakina managed in any of their four previous meetings.

She may be getting savvier, too. One of the dangers of a game built around a single weapon is that certain players might be able to neutralize it. Daria Kasatkina, Elena’s opponent in yesterday’s final, is just such an opponent, a resourceful defender and a first-class mover. When the two women played a three-and-a-half-hour epic in Montreal last summer, Kasatkina put three-quarters of first serves back in play, something that few women on tour could manage and one of the main reasons the match stretched so long. Rybakina survived, but she was broken ten times.

Yesterday, Kasatkina was as pesky as ever, getting almost as many balls back as she did in Montreal. But Rybakina took fewer chances with her first strike, perhaps as much to counter the wind as to adjust for her opponent. Whatever the reason, Elena made three-quarters of her first serves. She had never landed more than 61% against Kasatkina.

The Abu Dhabi final was an exaggerated example of a longer-term trend. Somehow, Rybakina is making way more first serves than ever before, sacrificing no aces and only a fraction of first-serve points won. The overall results speak for themselves:

Year    1stIn%  1st W%   Ace%   SPW%  
2024     66.8%   70.9%  10.3%  64.8%  
2023     56.8%   73.6%  10.5%  62.8%  
Career   57.8%   71.1%   8.4%  62.0%

It’s not a perfect comparison, because the entire 2024 season so far has been on hard courts. Her season stats will probably come down. But a ten-percentage-point increase in first serves in? Nobody does that. Kasatkina won just five games yesterday, and she won’t be the last opponent to discover that whatever edge she once had against Rybakina is gone.

Average ballast

As Ivo Karlovic can tell you, the best service in the world can take you only so far. Some first serves will go astray, some serves will come back, and then there’s the whole return game to contend with. Women’s tennis rarely features characters quite as one-sided as Ivo, but Vekic and Garcia illustrate the point, struggling to string together victories because their serves alone are not enough.

Here’s a quick overview of how the rest of Rybakina’s game stacks up against the average top-50 player over the last 52 weeks:

Stat     Top-50  Elena  
2nd W%    46.7%  48.4%  
DF%        5.2%   3.9%  
RPW       44.4%  44.2%  
Break%    35.5%  36.9%  
BPConv%   46.6%  43.5%

She’s somewhat better than average behind her second serve, as you’d expect from someone with such a dominant first serve. It’s aided by fewer double faults than the norm. On return, we have two separate stories. Taking all return points as a whole, Rybakina is almost exactly average, matching the likes of Barbora Krejcikova and Marta Kostyuk. The only category where she trails the majority of the pack is in break point conversions–and by extension, breaks of serve.

The discrepancy between Rybakina’s results on break points and on return points in general may just be a temporary blip. Most players win more break points than their typical return performance, because break points are more likely to arise against weaker servers. That hasn’t been the case for Elena in the last 52 weeks, and it wasn’t in 2022, either, when she won 41.9% of return points that year but converted only 40.5% of break opportunities.

Match Charting Project data indicates that she is slightly more effective returning in the deuce court than the ad court; since most break points are in the ad court, that could explain a bit of the gap. Charting data also suggests she is a bit more conservative on break point, scoring fewer winners and forced errors than her normal rate, though not fewer than the typical tour player. It may be that Rybakina will always modestly underperform on break opportunities, but it would be unusual for a player to sustain such a large gap.

In any case, she hasn’t struggled in that department in 2024. In 13 matches, she has won 46.9% of return points overall and 47.3% of break points. It’s dangerous to extrapolate too much from a small sample, especially on her preferred surface, but it may be that Rybakina’s single weak point is already back to the top-50 norm of her overall return performance.

The value of all this average is this: What Rybakina takes with her first serve, she doesn’t give back with the rest of her game. We’ve already seen how a standout rate of unreturned first serves–plus a bunch of average-level support from her second serve and ground game–translates into elite overall results on serve. A tour-average return game generates about four breaks per match. Elena has been closer to 3.5, but either way, that’s more than enough when coupled with such a steady performance on the other side of the ball.

I can’t help but think of Rybakina’s “other” skills as analogous to the supporting cast in team sports. Her first serve is an all-star quarterback or big-hitting shortstop; the rest of her game is equivalent to the roster around them. In baseball, a league-average player is worth eight figures a year. Though Elena’s return, for instance, doesn’t cash in to quite the same degree, it is critical in the same way. A superstar baseball player can easily end up on a losing team, just as Caroline Garcia can drop out of the top 50 despite her serve. Rybakina is at no risk of that.

A final striking attribute of Rybakina’s game is that her array of tour-average skills can neutralize such a range of opponents. Her weekend in Abu Dhabi was a perfect illustration, as she overcame Samsonova and Kasatkina, two very different opponents, each of whom has bedeviled her in the past. Elena is more aggressive than the average player, but she is considerably more careful than Samsonova; her Rally Aggression Score is equivalent to Swiatek’s. She was able to take advantage of the Russian’s rough patches without losing her own rhythm or coughing up too many errors of her own.

Against Kasatkina, she posted the most unexpected “average” stat of all. In a matchup of power against defense, defense should improve its odds as the rallies get longer. On Sunday, the two women played 15 points of ten strokes or more, and Rybakina won 8 of them. In her career, Elena has won 52% of those points–probably more by wearing down opponents with down-the-middle howitzers than any kind of clever point construction, but effective regardless of the means.

Rybakina won’t beat you at your own game. But she’ll play it pretty well. Combined with the best first serve in women’s tennis, drawing even on the rest is a near-guarantee of victory. Abu Dhabi marked her seventh tour-level title, and it will be far from her last.

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Ugo Humbert, Elo top-tenner

You probably don’t think of Ugo Humbert as a top-ten player, if you think of him at all. The 25-year-old left-hander cracked the ATP top 20 only a few months ago, and his title last week in Marseille gave him a modest boost to #18.

Elo is much more positive about the Frenchman. Today’s new Elo rankings place him 9th overall, just behind Hubert Hurkacz, the man he defeated to reach the Marseille final. Humbert has always been dangerous against the best, with a 22-25 career record facing the top 20, and a 10-12 mark against the top ten.

Humbert’s place in the Elo top ten might feel like a fluke; there’s a tightly-packed group between Hurkacz at #8 and Holger Rune at #13, and an early loss in Rotterdam could knock the Frenchman back out of the club. But historically, if a player reaches the Elo top ten, a spot in the official ATP top ten is likely in the offing.

I wrote about this relationship back in 2018, after Daniil Medvedev won in Tokyo. As his ATP ranking rose to #22, he leapt to #8 on the Elo list. In retrospect, it’s odd to think that “Daniil Medvedev will one day crack the top ten” was a big call, and it wasn’t that far-fetched: Plenty of people would’ve concurred with Elo on that one. He made it, of course, officially joining the elite the following July.

In that post, I called Elo a “leading indicator,” since most players reach the Elo top ten before the ATP computer renders the same judgment. This makes sense: Elo attempts to measure a player’s level right now, while the ATP formula generates an average of performances over the last 52 weeks. That’s a better estimate of how the player was doing six months ago. Indeed, for those players who cracked both top tens, Elo got there, on average, 32 weeks sooner. In Medvedev’s case, it was 40 weeks.

Most importantly for Humbert, Elo is almost always right. In October 2018, I identified just 19 players who had reached the Elo top ten but not the ATP top ten. Three of those–Medvedev, Stefanos Tsitsipas, and Roberto Bautista Agut–have since taken themselves off the list. One more has come along in the meantime: Sebastian Korda joined the Elo top ten in early 2023, but his ATP points total has yet to merit the same ranking.

Most of the Elo-but-not-ATP top-tenners had very brief stays among the Elo elite: Robby Ginepri qualified for just one week. The only exception is Nick Kyrgios, who spent more than a year in the Elo top ten, thanks to his handful of victories over the best players in the game. His upsets earned him plenty of notoriety, but his inability to consistently beat the rest of the field kept his points total deflated.

Humbert, in his much quieter way, fits the same profile. His serve means that he can keep things close against higher-ranked players, but he has struggled to string together enough routine wins to earn more of those chances. (Injuries haven’t helped.) Still, the odds are in his favor. In 32 weeks–give or take a lot of weeks–he could find himself in the ATP top ten.

* * *

Surfaces in South American Davis Cup

It dawned on me about halfway through the deciding rubber of the Chile-Peru Davis Cup qualifying tie: They were playing on a hard court! In South America! Against another South American side!

It made sense for Chile, with big hitters Nicolas Jarry and Alejandro Tabilo leading the team, and they did indeed vanquish the Peruvian visitors. But South America is known as a land of clay courts, the home of the “Golden Swing.” It seemed weird that an all-South American tie would be played on anything else.

As it turns out, it isn’t that unusual. Since the late 1950s, I found 252 Davis Cup ties between South American sides. I don’t have surface for 37 of them, almost all from the 1970s. Presumably most of those were on clay, but since that’s the question I’m trying to answer, I’m not going to assume either way.

That leaves us with 215 known-surface ties, from 1961 to the Chile-Peru meeting last weekend. (I’m excluding the matchup between Argentina and Chile at the 2019 Davis Cup Finals, since neither side had any say in the surface.) To my surprise, 37 of those ties–about one in six–took place on something other than clay. That’s mostly hard courts, but five of them were played on indoor carpet as well.

The country most likely to bust the stereotype has been Venezuela, which preferred hard courts as early as the 1960s. Ecuador also opted to skip clay with some frequency; it accounted for the first appearance of carpet in an all-South American tie back in 1979.

Chile has generally stuck with clay, but not always. The last time they hosted a South American side on another surface was 2000, when they faced Argentina on an indoor hard court. The surface probably wouldn’t have mattered, as Marcelo Rios and Nicolas Massu were heavy favorites against a much weaker Argentinian side. Though they won, the home crowd was so disruptive that the visitors pulled out without playing the doubles. Chile was disqualified from the next round and barred from hosting again until 2002.

The crowd last weekend was typically rowdy, but Jarry and Tabilo advanced without controversy. For some South American sides, hosting on hard courts may finally become the rule, not the exception.

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Felix Auger-Aliassime’s Achilles Heel

Also today: February 8-10, 1974

Felix Auger-Aliassime in 2023. Credit: aarublevnews

There may not be a more beautiful serve in tennis. When Felix Auger-Aliassime is hitting his targets, returners don’t have a chance. Auger-Aliassime has been particularly deadly on indoor hard courts, winning four such championships in 2022, then defending his Basel title last October.

Before returning to the winner’s circle at the Swiss Indoors, the Canadian’s 2023 season was one to forget. He struggled with a knee injury that knocked him out of Lyon and most of the grass-court season, where he would otherwise have figured to thrive. Between Miami–where he last reached his career-best ATP ranking of 6th–and Tokyo, he won just two matches in a dozen starts. We can’t hold much of that against him; when it wasn’t the injury, it was the recovery or the rust.

But he hasn’t played like a top-tenner in 2024, either. He lost to Daniel Altmaier to open his campaign, got dragged into a five-hour slog by Dominic Thiem in Melbourne, and then fell yesterday in Marseille to Zhang Zhizhen. The Chinese man, who lost to 1,107th-ranked Sebastian Dominko in Davis Cup last weekend, isn’t the sort of player who should threaten the likes of Auger-Aliassime, especially on an indoor hard court. Marseille has a reputation as a relatively slow surface for an indoor event, but according to my numbers, it played almost exactly as fast as Basel did last year.

With such a serve, the rest of Felix’s game should fall into place. But it hasn’t, and even the Canadian’s service games can get messy. Zhang broke him three times in ten tries yesterday, and he came close to a fourth. Last week in Montpellier, Auger-Aliassime saved just one of six break points before squeaking past Arthur Cazaux. Apart from an occasional glut of double faults, the serve itself rarely fails him. He reliably sends in aces on at least one of ten service points. Nearly one-third of his serves don’t come back. So what’s the problem?

The Canadian charge

There’s a certain style of play that has become recognizably Canadian, by some combination of the influence of Milos Raonic and the natural development of players who grow up practicing indoors. While Auger-Aliassime, Denis Shapovalov, and Leylah Fernandez–like Raonic before them–rarely serve-and-volley, they often venture far inside the baseline after serving. The move puts them in excellent position to swat away weak replies, at the cost of getting exposed by a deep return.

(The move also calls to mind Evonne Goolagong, perhaps the most casual serve-and-volleyer in the game’s history. Martina Navratilova said of her, “She didn’t serve-and-volley; she would sort of saunter-and-volley.”)

If Felix’s aggressive court position pays off, it should show up in his second shot stats. This may sound familiar, because I talked about the same thing in my piece about Sebastian Korda earlier this week. Though Korda’s serve isn’t quite the weapon that Auger-Aliassime’s is, the two men are similar in that their overall results don’t seem to reflect the strength of their opening deliveries. Korda, for all of his power, hits a second-shot (plus-one) winner or forced error 17% of the time that a return comes back, almost exactly in line with tour average.

Auger-Aliassime is similarly punchless. I ran the numbers again, this time back to 2019 instead of 2020, to capture most of the Canadian’s career. The plus-one winner rates are a bit different, but not enough to alter the story. I’ve also included more players for comparison:

Player                 Plus-one winner%  
Milos Raonic                      24.4%  
Denis Shapovalov                  21.5%  
Matteo Berrettini                 19.5%  
Carlos Alcaraz                    19.1%  
Holger Rune                       18.6%
Lorenzo Sonego                    18.4%  
Stefanos Tsitsipas                18.2%  
Felix Auger-Aliassime             17.6%  
Sebastian Korda                   17.3%  
-- Average --                     17.2%  
Jannik Sinner                     16.8%  
Daniil Medvedev                   16.3%

Given the potency of his serve and the positioning risks he takes, Auger-Aliassime finds himself in the wrong section of this list. He’s not as one-dimensional as Raonic, and he’s less explosive (and erratic) than Shapovalov, but couldn’t he play more like Berrettini? You might argue that Felix’s ground game is better than the Italian’s, and he can thrive without forcing the issue so quickly. That may be true–I believe the Canadian and his team think this way–but the numbers don’t bear it out.

Over their careers, Auger-Aliassime and Berrettini have hit unreturned serves at exactly the same rate. Yet the Italian wins two percentage points more often on his second shot. The overall picture is even more dramatic: Berrettini’s career tour-level rates of 69% serve points won and 88% service games held are each better than Felix has posted in any single season. Berrettini’s forehand is better, sure, but I can’t believe that accounts for the entire difference. The Canadian’s wait-and-see approach too often turns into a ten stroke rally that ends in favor of the other guy.

The Achilles heel

I promised you a weak spot of mythological proportions, and you’re going to get it.

The story of yesterday’s loss to Zhang was captured, oddly enough, in one of the service games that Felix won. At 1-3 in the second set, he raced to 30-love with two points straight from the textbook: big serve to the backhand, shallow reply, swat away a winner. He scored another classic plus-one at 30-15.

The two points he lost, though, show what happens when someone reads the serve, or when he misses the first serve and doesn’t do much with the second. At both 30-0 and 40-15, Zhang took advantage of a second serve to put the return at Felix’s feet. The first time, the Canadian could only keep the ball in play, and he lost a six-stroke rally. Two points later, Auger-Aliassime unforced-errored the backhand plus-one. He secured the hold with a better second serve at 40-30, but he isn’t always so lucky.

When returns land in the service box, Felix’s results are strong, even if he isn’t as aggressive as Berrettini or his fellow Canadians. Here are several stats profiling what happens to those weak replies: plus-one winner rates (P1 W%), plus-one error rates (P1 UFE%), and overall point winning percentage:

Player                 P1 W%  P1 UFE%  Pt W%  
Milos Raonic             43%      12%    64%  
Denis Shapovalov         36%      16%    60%  
Matteo Berrettini        34%      14%    60%  
Holger Rune              32%      13%    61%  
Carlos Alcaraz           32%      12%    66%  
Felix Auger-Aliassime    31%      13%    62%  
Sebastian Korda          31%      14%    61%  
Daniil Medvedev          30%       9%    63%  
Stefanos Tsitsipas       29%      11%    62%  
Lorenzo Sonego           29%      13%    57%  
-- Average --            28%      12%    60%  
Jannik Sinner            28%      11%    63%

These numbers are from 2019 to present, so Raonic’s stats are probably a caricature of the tactics he used at his peak. Still, it seems like Auger-Aliassime ought to be ending a few more of these points immediately. Either way, there’s no reason to complain about his ultimate outcomes–he wins more of these points than Berrettini does, and almost as many as Daniil Medvedev or Jannik Sinner. (Side note: Holy Alcaraz!)

Here is the same set of stats for returns that are not so shallow, but are still closer to the service line than the baseline. (The Match Charting Project calls these “deep”–as opposed to “very deep” returns.)

Player                 P1 W%  P1 UFE%  Pt W%  
Milos Raonic             31%      12%    56%  
Denis Shapovalov         24%      16%    54%  
Holger Rune              23%      13%    60%  
Matteo Berrettini        20%      14%    54%  
Lorenzo Sonego           20%      14%    54%  
Stefanos Tsitsipas       20%      11%    58%  
Carlos Alcaraz           18%      13%    57%  
Sebastian Korda          17%      16%    55%  
Felix Auger-Aliassime    17%      13%    53%  
-- Average --            16%      12%    55%  
Daniil Medvedev          15%       9%    56%  
Jannik Sinner            14%      10%    56%

Take away a couple of feet of court position, and Auger-Aliassime’s results look awfully pedestrian. He still hits more plus-one winners than average, but barely, and at the cost of more errors. He wins fewer of these points than average, and fewer than anyone in this selected group of players. If we make the reasonable assumption that the returns coming back from Felix’s serves are weaker than average–even if they land in the same sector of the court–those middle-of-the-pack numbers look even worse.

I hope you’ve stuck with me, because you’re about to find out how to beat Felix. It’s not easy, but it worked for Zhang. Here’s how players manage against very deep returns–the ones that land closer to the baseline than the service line:

Player                 P1 W%  P1 UFE%  Pt W%  
Milos Raonic             15%      14%    47%  
Denis Shapovalov         12%      14%    50%  
Matteo Berrettini        12%      11%    52%  
Stefanos Tsitsipas       11%      10%    52%  
Holger Rune              11%      11%    51%  
Sebastian Korda          10%      10%    50%  
Lorenzo Sonego            9%      14%    53%  
-- Average --             8%       8%    51%  
Carlos Alcaraz            8%       7%    54%  
Felix Auger-Aliassime     7%       9%    47%  
Daniil Medvedev           6%       6%    54%  
Jannik Sinner             6%       7%    52%

Auger-Aliassime plays these points like he’s Medvedev, but his baseline game can’t support those tactics. He wins these points at the same rate as late-career, physically compromised Raonic.

This is, in large part, the cost of that aggressive court position. Some players, like Alcaraz, can get away with it. Raonic couldn’t, but he put away so many cheap points that he could live with the drawbacks. It’s exaggerating only a bit to say that Auger-Aliassime gets the worst of both worlds: He doesn’t pick up an unusually high number of freebies, but then he finds himself on the back foot whenever someone manages to land a deep return.

That was the story of Zhang’s upset win yesterday. When the Chinese player hit a shallow reply, Felix won 11 of 15. When the return landed behind the service line, the success rate fell to just 8 of 25. It isn’t always that bad, and even when it is, a uptick in unreturned serves (or a strong return performance) can salvage the day. But opponents will only get better at reading the Canadian’s serve, and perhaps they will recognize that they needn’t attempt any heroics as long as they place the return deep in the court.

Auger-Aliassime isn’t going to wake up one day able to play like Medvedev, however much he might like to. He can, however, choose to play more like Raonic or Berrettini. His current approach is probably good enough for a long stay in the top 20: Elo ranks him 17th, at least until it updates with yesterday’s loss. But if he hopes to crack the top five, he’ll need to do more with the profits from that gorgeous serve.

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February 8-10, 1974: Sideshows take center stage

For a week in February 1974, the women’s tennis circuit had to make do without Billie Jean King. Fortunately, George Liddy was ready to pick up the promotional slack, and then some.

The Slims tour headed to Fort Lauderdale for an event on Chris Evert’s home turf–or, more accurately, her home Har-Tru. Billie Jean didn’t like her odds on clay in enemy territory, so it was a good time for a week off. In her absence, Evert provided the drubbings, Rosie Casals delivered the controversy, and–fulfilling what one newspaperman called Liddy’s “kinky dreams”–none other than Bobby Riggs showed up to sell more tickets.

The biggest story of the week took place off the court. Liddy was promoting more than just the S&H Green Stamps Tennis Classic; he also organized a track exhibition for the Friday night of the tournament. The big attraction was Riggs, who came to town for a much-ballyhooed race against famous miler Jim Ryun. (Earning a living as a professional track star could be complicated: Ryun had taken part in a tennis exhibition the previous June.) Ryun was a world-record holder and Olympic silver medalist, so in true Riggs fashion, some handicapping was in order. The 55-year-old hustler would get a half-mile head start.

Bobby was old, but he wasn’t that old. On February 8th, after a track clinic, a marching band, a pole-vault exhibition, and a 100-meter dash featuring some football players, the real business of the evening got underway. Riggs emerged, accompanied by a phalanx of young women and sporting a portable microphone to spice up the eventual television broadcast. He made a side bet with Rosie Casals and jokingly pleaded with organizers for an even bigger head start.

Ryun ran a respectable 4:03, but he never caught up with America’s most famous male chauvinist. Riggs ran his 890 yards in 3:22 for an easy victory.

“I’d say he needed another 200 yards,” Ryun said.

As for Riggs, he hadn’t been working out much since the Battle of the Sexes the previous September. His assessment: “I don’t think I’ve ever been this tired.”

* * *

Casals was tired, too. She had spent most of the week griping: The tour came back to Florida too often, she didn’t like to play on clay, it was cold and windy, and the crowd was partisan to the point of rudeness when she faced Jeanne Evert in the second round. Another of her complaints–about thoughtless scheduling–had merit. After a late-night doubles match on Thursday, she was first up on Friday’s order of play.

As if that weren’t enough, her routine defeat of Francoise Durr earned her a place in the semi-finals against Chrissie herself. “Nobody’s unbeatable,” Rosie said. But on Saturday, she salvaged just one game. Casals had to settle for a lesser prize–a local columnist declared her the champion of the press room.

The final had unexpected potential. Evert had been expected to run away with the title, and she hadn’t done anything to call that forecast into question. But second-seeded Kerry Melville looked like she might just make it close, allowing just two games to Nancy Gunter in her semi-final. Melville herself had said that the chance of anyone beating the home favorite in Fort Lauderdale were “very, very slim.” But after a near-flawless match, she felt differently: “If I play like I played today, I think I have a good chance of beating Chris.”

Alas, it wasn’t to be. At the hotel on Saturday night, Melville walked to the bathroom in the dark and fractured her toe. She withdrew, and the title went to Evert.

Liddy, though, had another ace up his sleeve. Riggs was already scheduled to play an exhibition match on finals day, against Miami Dolphins quarterback Bob Griese and wide receiver Ron Sellers. Bobby would play one-on-two, and the crowd would get the full raincoat-and-umbrella handicapping show. Everyone would go home with a smile on their face.

The biggest draw of the day, though, was Liddy’s last-minute replacement. Refunds were available, but only two ticketholders asked for their money back.

To play Evert, the promoter brought in none other than Althea Gibson, the two-time Wimbledon champion who had been the world’s best player in the late 1950s. Gibson had since earned her living as a golfer and made occasional attempts at a tennis comeback now that the sport had gone pro. At age 46, no one expected her to upset Chrissie, and she didn’t, winning just three games. But she impressed nonetheless.

“I don’t think there is anyone in women’s tennis today that serves it with that much pure power,” Evert said. “I was really surprised.” Althea wanted a rematch. After all, as one fan shouted during play, Gibson won more games off of Chris than Casals did.

Rosie, though, could take one consolation from the finals-day slate. The crowd immediately took to Althea, the obvious underdog and a legend to boot. Finally, a stadium full of Florida tennis fans was cheering against an Evert.

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Is Sebastian Korda Making Progress?

Also today: Talking Tennis interview

Sebastian Korda in 2023. Credit: Hameltion

It wasn’t long ago that Sebastian Korda was considered one of the best prospects in the men’s game. He won a tour level title before his 21st birthday, then fell one match short at the 2021 NextGen Finals. He reached two more finals in 2022, then began 2023 with a near-miss, a momentous three-hour clash with Novak Djokovic in Adelaide that ultimately went to the veteran.

That result, plus a quarter-final run in Melbourne and another runner-up finish last October in Astana, nudged Korda up to a career-high ranking of 23. While he has since dropped the points from Down Under and fallen out of the top 30, my Elo ratings keep him in the top 25, just ahead of the man who defeated him in Kazakhstan, Adrian Mannarino.

This all represents a step forward for the American, especially since he struggled throughout last year with a wrist injury. Compared to expectations, though, it’s a bit underwhelming. Korda’s father, Petr, is a grand slam champion; Sebastian has said he’d like to surpass him and win two. At age 23, he has plenty of time to develop, but eight of the men ahead of him in the rankings–including three of the ATP’s top seven–are younger still. For all the veteran exploits we’ve seen in the last decade of the ATP tour, superstars tend to make themselves known at an early age.

Last night, Korda recorded his 100th tour-level victory, a milestone that reminds us how much he has accomplished in his budding career. The match itself, however, pointed at some of his limitations. The American edged out big-serving French qualifier Hugo Grenier in the Marseille first round, 6-3, 2-6, 7-6(3). The player Korda aims to be would have progressed with ease. As it happened, he won 89 points to his opponent’s 92, marred by an error-spattered string in which he lost seven straight games. Grenier played well, but he is ranked outside the top 150. Korda didn’t look much better.

What’s missing? The 23-year-old has all the tools to climb higher: a six-foot, five-inch frame; an overpowering serve including a hard slice delivery that looks as if it were inherited directly from his left-handed father; a flexible, assured backhand; and a willingness to step into the court to take control of points. To watch him play, there’s very little separating Korda from, say, Taylor Fritz, yet Fritz is a top-tenner. Is it just a matter of time until Korda closes the gap, or does his game need to change?

Progress report

Let’s start with the positive: Korda’s serve is getting the job done. Yesterday, more than one-third of his serves didn’t come back. That’s in line with the average of the several other charted matches from the last 52 weeks. Only a handful of men end the point so often with their first shot; Fritz and Ben Shelton top 30% but still trail Korda. In a losing effort against Hubert Hurkacz in Shanghai last fall, more than 45% of the American’s serves were unreturned.

Those numbers represent a major step forward. Facing Hurkacz at the Australian Open last year, fewer than one-quarter of his serves ended the point. Korda finished below the 25% mark in matches against Daniil Medvedev and Karen Khachanov at the same event, too. It’s ironic that he won that one against Hurkacz and lost in Shanghai, but there’s no counter-intuitive moral to glean: Unreturned serves are an incontrovertible good.

The 23-year-old’s results are less reliable when the ball comes back. Even when presented with an attackable return, Korda sometimes hesitates. In two matches against Hurkacz last fall, Korda didn’t hit a single plus-one winner or forced error behind the second serve. (The high rate of unreturned serves means that his best deliveries aren’t coming back as sitters, but that hardly means that the remaining returns are all so daunting.) Grenier put 21 second serves back in play yesterday, only one of which the American ended with his second shot. Despite the qualifier’s overt aggression–he occasionally swung wildly for winners against Korda’s seconds–the average point on Korda’s deal ran to 4.3 strokes, an unusually high figure for such a strong server.

Taking first and second serves together, how much does Korda sacrifice with his conservative-seeming mindset on plus-ones? I calculated the percent of 3rd shots (plus-ones) and 5th shots that went for winners or forced errors across all charted matches since 2020. Here are results for Sebi, plus those of a few comparable players and the tour average:

Player                 3rd W%  5th W%  
Hubert Hurkacz          19.0%   20.0%  
Stefanos Tsitsipas      18.5%   20.1%  
Taylor Fritz            18.2%   17.1%  
Sebastian Korda         17.1%   16.9%  
-- Average --           17.1%   17.3%  
Felix Auger-Aliassime   16.8%   17.1%

Korda is just not as aggressive as the more successful of his tall, big-serving peers. He out-winners Felix Auger-Aliassime, but I would argue (and will do so at length, one of these days) that the Canadian’s approach is holding him back, as well. It isn’t that Korda is entirely passive on the plus-one, but given the relatively weak return quality he faces, he should be putting away more than a tour-average rate of second shots.

There is, however, a reason for his unwillingness to swing bigger, and that’s where we’ll turn next.

Something wild

Here’s the same table with two more columns: one for each player’s unforced error rate on the 3rd shot of the point, and another for the unforced error rate on the 5th shot:

Player                 3rd W%  3rd UFE%  5th W%  5th UFE%  
Hubert Hurkacz          19.0%     12.8%   20.0%     11.8%  
Stefanos Tsitsipas      18.5%     11.4%   20.1%     10.2%  
Taylor Fritz            18.2%     11.1%   17.1%      8.8%  
Sebastian Korda         17.1%     13.8%   16.9%     12.3%  
-- Average --           17.1%     10.8%   17.3%     10.4%  
Felix Auger-Aliassime   16.8%     10.9%   17.1%     11.6%

Yikes! Korda is wilder on these shots than the other players, so much so that he ends more points with the plus-one shot than everyone on this list except for Hurkacz. Of players with some degree of tour-level success, only Marin Cilic misses more plus-ones. Denis Shapovalov and Alejandro Davidovich Fokina are roughly equivalent to Korda in this department.

We’ve taken a roundabout path to reach a more general fact about the American’s game: He misses a lot of shots. As a fraction of all groundstrokes, Korda ends points in his favor about 10% more often than the average ATPer. But he commits 20% more unforced errors. His plus-ones are of a piece with his entire ground game, even if they’re a bit wilder. Racking up so many unforced errors without a correspondingly large winner count means, by definition, that his baseline game is a liability. Only that big pile of unreturnable serves is keeping him above water.

Fortunately, Korda is still young, and his game is not set in stone. He missed 13% of his plus-ones yesterday, but that number is trending in the right direction. Here are his winner and unforced error rates on the third shot of the rally, as ten-match rolling averages going back to the 2021 NextGen Finals:

You don’t need a tour guide to spot the good news here. Korda’s plus-one error rate used to be outrageously high. It’s still higher than he like it to be, but it’s dramatically better, and getting it under control hasn’t cost him much on the other side of the ledger. As he puts the wrist injury fully behind him, there may be even more room for improvement.

The ceiling

I’ve focused on the serve–and Korda’s approach behind it–because that’s the side of his game that will determine how high he climbs. In his career at tour level, he has won 38% of return points, a figure that means he’ll break often enough to win matches when he serves well. Maintaining a 38% rate will get tougher as the quality of his opposition rises, but that may not be a problem: He has already excelled against top tier competition. As Alex Gruskin points out, he’s 18-21 against top-20 players, a record that indicates he’s already able to compete at that level, even if his results against the rest of the pack (and his health) aren’t consistent enough to support a corresponding ranking.

Korda may improve his return game, but if he is to crack the top ten and have a real shot at those two major titles, his serve will make the difference. In the last 52 weeks, he has won 66% of return points and held 83% of service games, numbers that place him among the top half of the top 50… but not much higher. The serve itself needs no improvement, as we’ve seen. The difference between Korda and someone like Fritz or Tsitsipas is what happens when the serve comes back. The 23-year-old is making progress, but he has more steps to take before he can reach the enormous potential that once seemed so assured.

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Talking Tennis interview

I recently spoke with John Silk of Talking Tennis, and in a one-hour interview ,we covered all things Tennis Abstract: how to get the most out of the site, Elo ratings, common beliefs about tennis stats, and the Tennis 128. Watch it here:

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Yes, Jannik Sinner Really Is This Good

Also: Australian Open coverage recap

Jannik Sinner

Don’t let Daniil Medvedev’s near-miss in the Australian Open final fool you: Jannik Sinner is the best player in the world right now. Like Sunday’s championship match, it’s close–but it might not be close for long.

I wrote in December about what I called the “most exclusive clubs” in tennis. Since 1991, when the ATP began keeping these stats, Andre Agassi and Novak Djokovic have been the only two players to finish a season in the top three of both hold percentage and break percentage. (Agassi did it twice.) Well, in the last 52 weeks, Sinner ranks second in hold percentage behind Hubert Hurkacz, and he stands third in break percentage, trailing only Medvedev and Carlos Alcaraz. It’s not a calendar year so we can’t officially add him to the list, but he’s playing as well on both sides of the ball as anyone ever has, apart from two all-time greats.

Oh, and on hard courts, Sinner out-holds even Hurkacz. He gets broken less than anyone in the game, securing his serve 89.9% of the time.

But wait–it’s even better than that. Alex Gruskin pointed out that since Wimbledon, Sinner’s hold percentage is 91.1%, within shouting distance of John Isner’s career mark of 91.8%. Isner cracked the top ten by combining that monster serve with a return that only a mother could love. Sinner, on the other hand, pairs absolutely dominant serving with one of the best returns in the game. Ever wonder what would happen if Big John had an elite return? Now you know.

Starting the clock at Wimbledon might raise an eyebrow–is that just the line that spits out the most impressive number?–but it’s a sensible way to divide the data. In June, not long before the Championships, Sinner rolled out a new, simplified service motion. While the measurements of the new delivery are not overwhelming–one more mile per hour, four centimeters closer to the line, a 0.7 percentage-point increase in first serves in–the results have been devastating. His serve has always been good; perhaps a few minor tweaks were all it took to make it great.

Winning how?

First, a bit of a puzzle. In the last 52 weeks, Sinner ranks fifth on tour in serve points won, with 68.3%. (Why not first or second, in line with his hold percentage? We’ll come back to that.) Yet despite the Isner comparisons, he doesn’t get it done the easy way. He hits aces just 8.4% of the time. That’s equal to the average of the ATP top 50, and it’s fewer than Djokovic.

The answer doesn’t lie in unreturned serves, either. Some players do get more free points than their ace counts imply. Stefanos Tsitsipas, for instance, ranks well down the ace list, finishing just 9% of his serve points that way. But he looks much more elite when we measure how many don’t come back–almost one-third, in his case. Sinner’s 29.6% rate of unreturned serves is above average, but it’s hardly the stuff that record-breaking hold numbers are made of. The next man on the list, for comparison’s sake, is Frances Tiafoe.

What about plus-ones? Sinner serves big, but relatively speaking, his groundstrokes are even bigger. Can we explain his serve-game success by the rate at which he ends points with his second shot?

Still no! He wins 40% of his serve points by the third shot of the rally. Again, that’s a solid mark: Djokovic and Alcaraz are about the same. On the other hand, so is Jiri Lehecka, and Tiafoe is even better.

Once a point reaches the fourth or fifth shot–especially if it began with a second serve–winning it is more about contesting a rally than converting any lingering advantage of the serve. If the returner puts the fourth stroke of the point in play, he has a 52% chance of winning it. Big servers still get some easy putaways, but opportunities disappear as the rally develops. When that happens, winning service points relies on a different set of skills–assets that Sinner, unlike many a big server, amply possesses.

Sinner, then, has the whole package, even if no single one of his weapons stands out like the Isner serve. He serves big enough to clean up 40% of points with his first or second shot. It the point lasts longer, he has probably hung on to more of an advantage than most players do: His heavy, deep groundstrokes see to that. In a really long rally, okay, maybe the edge goes to Medvedev or Alcaraz, but who else is going to outlast the Italian?

Most players excel at some stage of service points, but not all. The following graph illustrates how service points typically develop, by showing the server’s chance of winning the point when each successive shot is put in play. Based on charted men’s matches since 2021, servers win 64.2% of points. That goes up to 66.5% if they land a serve; it goes down to 52.5% if the return comes back. Several strokes later the server’s advantage is mostly gone: If he puts the 7th shot of the point in play, his chances of winning are 57.4%; if the returner comes back with an 8th shot, the server’s odds are down to 45%.

I’ve shown that progression along with specific numbers for Hurkacz, in order to demonstrate how these things go with our usual image of a big server:

While the differences between Hurkacz and tour average are modest, you get the idea. Early in the point, a big server cleans up; the longer the rally goes, the further his results fall below the line.

Now, the same graph with Sinner’s results from 2021 to the present:

He doesn’t start as high as Hurkacz, but he does do a little better than average. Crucially, he never falls below the average line, and the longer the point extends, the more he surpasses it.

I hope you’ve stuck with me this far, because the payoff is worth it. Same graph, only instead of Sinner’s three-plus-year average, we have his numbers since the beginning of 2023:

At the beginning of the point, Sinner is almost equal to Hurkacz. From then on, he takes over. A surprising gap comes early, at the two-plus rally mark, indicating that he doesn’t make many mistakes with his plus-one shot, even if he doesn’t put away an overwhelming number of them. No matter how long the point continues, the Italian outperforms tour average for that particular situation.

In tennis, it’s almost impossible to be good at everything. You can put together a nice, quite lucrative career by merely getting close to average in most categories and having one or two standout weapons. Sinner, we’re beginning to see, is not just good at everything, he is verging on great.

Break points

We now know why Sinner is winning so many serve points. But I mentioned another mystery we have yet to resolve. The Italian ranks fifth in the last 52 weeks in serve points won, the middle of a tightly-packed trio with Nicolas Jarry and Taylor Fritz, about one percentage point behind Hurkacz, Tsitsipas, and Djokovic. Yet he challenges Hurkacz for the top spot in the closely related, more consequential category of hold percentage:

Player               Hld% Rk   Hld%  SPW Rk   SPW%  
Hubert Hurkacz             1  89.1%       1  69.6%  
Jannik Sinner              2  88.8%       5  68.3%  
Stefanos Tsitsipas         3  88.4%       2  69.5%  
Novak Djokovic             4  87.6%       3  69.4%  
Nicolas Jarry              5  87.1%       4  68.4%  
Alexander Zverev           6  86.1%       7  67.4%  
Taylor Fritz               7  86.0%       6  68.2%  
Christopher Eubanks        8  85.8%       8  67.1%  
Carlos Alcaraz             9  85.7%      10  67.0%  
Tallon Griekspoor         10  85.1%      12  66.7%

The lists are almost identical, except for Sinner’s placement. He wins points at almost the same rate as Jarry and Fritz, yet he holds serve more often than either one.

As mysteries go, this isn’t a tough one. Not all points are created equal; if you win more of the important ones, you’ll outperform the players who don’t. Nobody knows that better than Sinner, who upset Djokovic in Turin despite winning exactly the same number of points, then beat him again at the Davis Cup with just 89 points to Novak’s 93. He out-pointed Medvedev yesterday 142 to 141.

Sinner wins these matches by saving break points at a remarkable clip. While winning 68.3% of serve points overall, he has held off 71.7% of break chances, including 36 of 40 in Melbourne. No one else on tour tops 69%, and Hurkacz comes in at 65%. On average, top-50 men save break points two percentage points less than they win typical serve points (63.5% to 65.5%), mostly because stronger returners generate more break points.

The question, then, is whether this is sustainable. ATP numbers indicate that Sinner goes bigger on break points, averaging 125 mile-per-hour first serves in those situations rather than his usual 122s. It seems to be working, but it can’t be that straightforward. Surely he isn’t the first player to arrive at the strategy of simply hitting harder, and besides, that usually comes at a cost. Will he continue to land enough of those bigger first serves to justify the payoff?

I can’t answer that question, but I can tell you what usually happens after a season of break-point overperformance: It doesn’t last. Taking over 2,600 player-seasons since 1991, 582 (21.7%) of players saved more break points than they won serve points overall. 183 (6.8%) matched Sinner’s mark of saving at least two percentage points more than their serve-points-won rate.

Of those 183, just eleven repeated the feat the following year. None of them were big servers, and nobody managed it three years in a row. The average following-year performance of the 183 men was 1.5 percentage points fewer break points saved than their rate of serve points won–just a tick better than tour average.

Unless Sinner has developed a new secret sauce–to be clear, with Darren Cahill in his corner, I’m not ruling it out!–that’s probably the fate that awaits him. In more than three decades, only 23 men have saved at least 71.7% of the break points they faced for a full season. The Italian probably won’t keep that up, and his out-of-this-world hold percentage will fall to something more plausible, in the 86-87% range.

Fortunately, that’s still exceptionally good. The 22-year-old serves like Jarry or Fritz while racking up as many return points as Djokovic. Take away the break point magic and you still have a contender for every slam. Sinner continues to lurk in fourth place in the official ATP rankings, but as of today, he is number one on the Elo list. Before long, those positions will converge, and it won’t be because his Elo rating goes back down.

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AO recap

I hope you’ve enjoyed my coverage throughout the Australian Open. I’ll continue to write this sort of thing throughout the year, though not always every weekday!

In case you missed it, here are the ten other articles posted since the action in Melbourne began:

Thank you for reading.

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Aryna Sabalenka Under Pressure

Also today: January 26, 1924

Aryna Sabalenka at Wimbledon in 2023. Credit: Adrian Scottow

It felt like a pivotal moment. Aryna Sabalenka had taken a 5-2 first-set lead in yesterday’s Australian Open semi-final against Coco Gauff. Gauff kept the set going with a strong service game for 5-3. Sabalenka lost the first point on her serve, but bounced back with a plus-one backhand winner.

At 30-15, the American struck again. She took advantage of a Sabalenka second serve to drag the Belarusian into a backhand rally, ultimately drawing an unforced error on the ninth shot and putting the game back in play.

Then, still just two points from the set, Sabalenka double-faulted.

The narrative practically writes itself. Aryna hits hard, aims for the lines, and keeps points short. Let her do that, and she will destroy you. Her first five opponents in Melbourne managed a grand total of 16 games against her. On the other hand, if you keep the ball in play, she’ll start pressing, trying too hard to dictate with her serve, going for too much when a smackable groundstroke presents itself.

Gauff, by this reading, is Sabalenka’s nightmare opponent. She won the US Open final by denying the Belarusian one would-be winner after another. Not only can she take Sabalenka’s game away from her, but Coco–at least on a good day–won’t give it back on her own serve. When she lets loose, Gauff wields just as much power as her more tactically aggressive opponent.

As it turned out, Sabalenka did lose that service game. Several twists and turns later, Gauff led the set, 6-5. Only then did Aryna regroup, winning four straight points from 30-love to force a tiebreak, then dropping just two more points to clinch the set. Gauff kept the second set close, but Sabalenka never allowed her to reach break point. The contest closed with a narrative-busting move: Facing match point, Gauff pulled out a 12-stroke rally, the kind of point that has been known to steer her opponent off course. But instead of compounding the damage, Sabalenka came back with two unreturned serves. Game over.

What to believe, then? Was the apparent first-set turning point a reflection of the true Sabalenka? Or is this the new Aryna, who slams the door when challengers sniff opportunity? Or is it something else, the all-too-common story in which someone looks like a clutch hero or a constant choker, only for us to discover, after crunching all the numbers, that she’s impervious to momentum and plays pretty much the same all the time?

Recovering at a disadvantage

Sabalenka’s serve games do follow a pattern after she loses a longish rally. But the results are not entirely straightforward.

On the next point (assuming the lost rally didn’t end the service game), Aryna is more likely to miss her first serve:

Year   1stIn%  post-rallyL-1stIn%  Change  
2019    61.2%               55.9%   -8.6%  
2020    61.5%               57.0%   -7.3%  
2021    58.6%               52.6%  -10.3%  
2022    60.0%               59.9%    0.0%  
2023    61.1%               61.3%    0.4%  
2024    63.3%               62.5%   -1.2%
----  
TOTAL   60.5%               57.6%   -4.8%

Most of the effect is concentrated in the earlier years of her career on tour. Yesterday, the trend ran in the opposite direction: She made nearly 76% of her first serves overall, but after Gauff won a rally, she landed 88% of them.

The trend is clearer–and persisting to the present–when we look at double faults after losing a rally:

Year     DF%  post-rallyL-DF%  Change  
2019    8.6%            10.4%   20.8%  
2020    6.2%             8.4%   36.9%  
2021    7.9%            11.8%   50.3%  
2022   10.7%            10.1%   -5.5%  
2023    6.2%             7.2%   16.5%  
2024    3.4%             8.3%  144.7%  
----
TOTAL   7.9%             9.6%   22.5%

2022 was Aryna’s year of the yips; she was more likely to bunch double faults together than hit them in particularly nervy spots. (Put another way: Every spot was a nervy one.) The 2024 number will surely come back to earth, but it is still revealing: Sabalenka has made so much progress in this aspect of her game, but her second-serve struggles continue when she faces the threat of getting dragged into another rally.

Some of these effects persist even longer. From those service games that last long enough, here are Sabalenka’s first-in and double-fault percentages two points after losing a long rally:

Year   1stIn%  +2 1stIn%  Change    DF%  +2 DF%  Change  
2019    61.2%      55.8%   -8.8%   8.6%    8.7%    1.2%  
2020    61.5%      50.5%  -17.9%   6.2%    7.2%   17.1%  
2021    58.6%      56.0%   -4.5%   7.9%    8.7%   10.5%  
2022    60.0%      63.1%    5.3%  10.7%    7.8%  -27.1%  
2023    61.1%      59.2%   -3.2%   6.2%    8.4%   35.6%  
2024    63.3%      57.1%   -9.7%   3.4%    2.4%  -30.1%  
----
TOTAL   60.5%      57.1%   -5.6%   7.9%    8.0%    2.0%

She continues to miss more first serves even two points after the rally setback. To some degree, the memory should have dissipated–after all, something else happened on the intervening point. On the other hand, she’s back in the same court. If a reliable serve didn’t work in the deuce court at 30-love, there’s reason to doubt it at 30-all.

The double fault trends are less clear, in part because our sample size is shrinking and double faults are blessedly rare. If nothing else, it’s safe to conclude that the explosion of double faults on the point after the lost rally doesn’t continue to nearly the same degree.

Tallying the cost

Now, this all seems bad. Sabalenka possesses one of the best first serves in the game; her whole attack is built around it. Her emergence as a superstar came after she got control of the service yips and cut her double faults down to manageable levels. After losing a long rally, she needs her serve more than ever, and–at least by comparison with other situations–it isn’t there for her.

Except… it doesn’t matter! At least not on the first point. Here is the bottom-line figure of service points won:

Year    SPW%  post-rallyL-SPW%  Change  
2019   59.6%             63.8%    7.2%  
2020   60.3%             56.6%   -6.0%  
2021   61.5%             61.3%   -0.3%  
2022   57.2%             59.9%    4.7%  
2023   63.7%             63.9%    0.4%  
2024   66.7%             70.8%    6.3%  
----
TOTAL  60.7%             61.7%    1.6%

Fewer first serves, but more serve points won. It isn’t supposed to work like that, but Sabalenka bounces back strong from lost rallies. A shift of +1.6% in her favor is solid enough, and it’s even better if you look solely at the last three years.

Part of the explanation is that she tightens up the rest of her game–exactly the opposite of what my off-the-cuff narrative suggests. Under pressure, I hypothesized, she would try too hard to end points. Instead, after losing a long rally, she’s more willing than usual to play another one: She commits 14% fewer plus-one errors than her usual rate, implying a lower rate of aggression when she has an early chance to put the point away.

On the second point after losing a long rally, the bottom-line outcomes are more mixed:

Year    SPW%  +2 SPW%  Change  
2019   59.6%    53.9%   -9.5%  
2020   60.3%    55.3%   -8.3%  
2021   61.5%    58.5%   -4.9%  
2022   57.2%    61.5%    7.4%  
2023   63.7%    60.7%   -4.7%  
2024   66.7%    71.4%    7.1% 
---- 
TOTAL  60.7%    58.2%   -4.0%

While these aren’t as rosy as the next-point results, focus on the last few years. Since the beginning of 2022, Aryna has won more service points than usual when she returns to the serving direction where she recently lost a long rally–despite landing fewer first serves. She is even stingier with plus-one errors on these points, coughing up 29% fewer than usual.

These trends did not hold in yesterday’s semi-final. While Sabalenka made more first serves on the two points after Gauff outlasted her in a rally, fewer of them ended in her favor: 4% less on the first point, 12% less on the second. We can’t read too much into single-match totals with stats like these: 4% is a difference of one point. And Gauff is a far superior returner and baseline player than the typical WTAer, one who is unlikely to lose focus after going toe to toe with Sabalenka for a point or two. The average player pushes Aryna to a seventh shot barely one-tenth of the time; Gauff did so on one of every six points yesterday.

All of this leads us to an unexpected conclusion: Does Aryna Sabalenka have nerves of steel? First serves and double faults are just components in a larger picture; when we measure her results by points won, Sabalenka serves more successfully right after an opponent makes her uncomfortable. The yips are gone, and the on-court histrionics are a diversion that deceived us all. Aryna under pressure may be even more fearsome than her typical, terrifying self.

* * *

January 26, 1924: Suzanne’s longest day

Suzanne Lenglen wasn’t accustomed to spending much time on court. In eight tournaments since the 1923 Championships at Wimbledon, she had lost just ten games. Her doubles matches, especially with net maven Elizabeth Ryan at her side, were often just as lopsided. She never missed, she could put the ball anywhere on the court, and most opponents were lucky just to win a single point.

Lenglen and Ryan in 1925 at Wimbledon. Colorization credit: Women’s Tennis Colorizations

In January 1924, Lenglen eased her way back onto the circuit. Battling some combination of illness, anxiety, and hypochondria, she didn’t return to singles action until February. (She’d win her first three matches before dropping a game.) But she was a celebrity on the French Riviera, and she was prevailed upon to compete in doubles. She won the mixed at the Hotel Beau-Site tournament in Cannes to ring in the new year, and she entered both the women’s doubles–with Ryan–and the mixed at the Hotel Gallia tournament a few weeks later.

On the 26th, Lenglen and Ryan completed their waltz through the draw, defeating a British pair, Phyllis Covell and Dorothy Shepherd-Barron, 6-3, 6-4. Suzanne’s most aggravating foe was another Brit, a line judge with the temerity to call a foot-fault on the five-time Wimbledon champion. She tried to get the man removed and ultimately had to settle for his “voluntary” departure. “It is unfair,” she said. “The English are pigs.”

Her nerves would be tested even more severely in the mixed doubles final. Lenglen partnered Charles Aeschlimann of Switzerland, while Ryan teamed with the 43-year-old Canadian Henry Mayes. Both men were better known on the Riviera than in the tennis world at large, more clubbable than talented. Lenglen and Ryan–herself one of the top few woman players in the world–would be the stars of the show.

Lenglen and Aeschlimann took the first set, 6-4; Ryan and Mayes came back with a 6-1 frame of their own. The underdogs–that is, the team without Suzanne–built up an early lead in the third, thanks to Aeschlimann’s inconsistency and Ryan’s glittering play. Mayes served for a 4-2 advantage, but a lucky netcord halted their momentum, and the deciding set settled into a rhythm it wouldn’t break for 20 more games.

Only at 13-14 did Ryan finally give in. She gifted a double fault to her opponents, and Mayes’s fatigue–he had played a four-set men’s doubles final beforehand–began to tell. Lenglen and Aeschlimann broke serve, securing the 6-4, 1-6, 15-13 victory. It would stand as the longest set of Suzanne’s unparalleled career.

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How To Play One-Set Shootouts Like Daniil Medvedev

Daniil Medvedev in 2023, practicing… something. Credit: Hameltion

In yesterday’s Australian Open quarter-final match against Hubert Hurkacz, Daniil Medvedev came through with his second five-set win of the tournament. In the decider, Hurkacz’s level dropped, Medvedev kept his ground game tight, and the Russian converted the one break point on offer. Four hours of tennis, compressed into a few crucial moments, and Medvedev has a place in the semi-finals.

Not long ago, Medvedev gained a reputation as a disappointment in deciding sets. He lost 11 of 15 three- and five-setters in 2022, and yesterday’s match was the first time in nine tries–going back to Melbourne two years ago–that he had beaten a top-ten player in a climactic set.

But such trends are easy to exaggerate. For one, three of those eight consecutive losses were clustered at the 2022 Tour Finals, where the Russian managed, remarkably, to drop third-set tiebreaks in all of his round-robin matches. Not the best way to ensure a restful offseason, but hardly an indictment of his ability to hang around late into matches with the best players in the game.

Further, except for the 2022 season, Medvedev has developed a knack for cleaning up close matches with everybody else:

Year   Decider W-L  Decider W%  
2024           2-0      100.0%  
2023          14-6       70.0%  
2022          4-11       26.7%  
2021          14-5       73.7%  
2020           9-4       69.2%  
2019         10-11       47.6%  
2018          16-9       64.0%  
2017          13-6       68.4%  
2016          23-9       71.9% 
---- 
Total       105-61       63.3%

2016 shouldn’t really count, since it’s a mix of ITFs, Challengers, and early forays onto the main tour, but given the results, I figured it was worth including. Wherever you draw the line, it’s hardly the case that Medvedev struggles in such matches. Recently, I looked into what a player’s third-set record “should” be, given their skill level, and a mark above 60% is better than expected for nearly anyone.

You might argue that the Russian shouldn’t have racked up so many deciders. He was expected to finish off Emil Ruusuvuori much more quickly than he did in the second round in Australia, and even on clay, he should never have gotten dragged to a fifth set at Roland Garros by Thiago Seyboth Wild, much less lost it. But everyone takes the scenic route sometimes. 14 of Medvedev’s deciding sets last year came against the top 50, 10 of them against the top 20.

The final set shift

When a match is reduced to a one-set shootout, it becomes a bit less serve-centric. This is a persistent finding in all high-pressure situations, from tiebreaks to break points to fifth sets. Servers get a bit more cautious, returners heighten their focus, and quick points are harder to come by.

The effects are small but real. In the 1,200-plus men’s deciding sets since 2017 logged by the Match Charting Project, servers win 1.1% fewer points in the final set that they did in the first two or four. They land fractionally more of their first serves, but only by increasing their margins: The percent of unreturned serves falls by more than 5%. The average rally increases from 4.1 strokes to 4.3.

There are two fundamental ways to benefit from those changes. First, you can buck the trend, continuing to serve big while your opponent succumbs to the natural tendency toward caution. That’s part of the reason that John Isner and Roger Federer were two of the very few players to win more tiebreaks than expected over long periods of time. It’s not easy, especially if fatigue is setting in. But if you can keep serving the way you did for two or four sets, you have a minor edge in the decider.

Second, you can be the type of player who excels in deciding-set-style tennis. If you had to pick between Medvedev and Hurkacz in a contest where more serves would come back and points would last longer, the choice is simple, right? It’s no guarantee, to be sure: The shift is a minor one, and it may not show up in any given match. Yesterday, more points were decided in four shots or less in the fifth set than in the first four. But on average, the trend moves in the other direction, right into the Russian’s wheelhouse.

Evidence shows that Medvedev follows these prescriptions, maintaining his attack on serve while taking advantage of more cautious opponents. Other top players, to varying degrees, do the same.

Let’s start with the basics. For each stat, I calculated every player’s performance in deciding sets, and in all previous sets. The numbers I’m about to show you are the ratio between those numbers, a measure of how much their tactics change when the final set begins. Positive numbers mean they do more of it in the decider, negative means they do less. We’ll look at the four Australian Open semi-finalists, plus Carlos Alcaraz (because of course) and Hurkacz (because of his deciding-set notoriety). Keep in mind that Novak Djokovic’s figures are limited to matches since 2017.

Here are the rate of serve points won, and the rate of first serves in:

Player             SPW%  1stIn%  
Carlos Alcaraz     3.9%    4.4%  
Jannik Sinner      2.6%   -1.2%  
Novak Djokovic     1.5%   -1.1%  
Hubert Hurkacz     0.8%   -1.9%  
-- Average --     -1.1%    0.7%  
Daniil Medvedev   -1.2%   -1.7%  
Alexander Zverev  -4.5%    3.2%

Medvedev is in line with tour average when it comes to winning service points: He doesn’t hold on to as many in deciding sets. Average isn’t bad in this case, though it looks mediocre in this company. A more encouraging sign, at least in terms of the tactical approach, is the change in first serves in. The Russian, in line with Djokovic, Hurkacz, and Jannik Sinner, seems to take a few more chances in the shootout. Alcaraz defies gravity, serving more conservatively yet winning more points, and Zverev looks out of place, a caricature of prudence.

Now let’s look at the percentage of serves that don’t come back (Unret%), as well as the percent of service points won in three shots or less (SPW% <=3):

Player            Unret%  SPW% <=3  
Novak Djokovic     10.9%      5.4%  
Carlos Alcaraz      0.2%      1.0%  
Daniil Medvedev    -0.6%     -2.0%  
Hubert Hurkacz     -1.1%      0.2%  
-- Average --      -5.7%     -3.6%  
Jannik Sinner      -7.4%      0.3%  
Alexander Zverev  -13.4%    -11.2%

The first rule of writing about men's tennis: Whatever the topic, you'll eventually end up showering praise on Djokovic. In recent years, he has learned how to get more out of his serve, and he turns that knob even further in deciding sets. Most players struggle to simply stay above water in the final set; Djokovic starts serving bigger.

Medvedev's rate of unreturned serves is the sort of positive sign it takes a connoisseur to appreciate: "-0.6%" doesn't turn up on many Hall of Fame plaques. But when the typical player serves so much more carefully, the Russian's consistency works to his advantage. His three-shots-or-less win rate does not stand out as much, but it is still less of a step backward than the typical tour player takes.

Once again, deciding-set Alexander Zverev is an unusual beast.

Opportunistic returning

If the challenge on serve is to keep attacking in the final set, the task on return is to take advantage of an opponent who probably isn't doing that. Ideally, that might mean more aggression on the return, but a 1% or 5% weaker first serve is still only so playable. Instead, players should make sure not to squander the chances they're given: Make more returns, then tighten up the ground game for the inevitable rallies.

Here are three stats to illustrate deciding-set return tendencies, again expressed as ratios between how each player performs in the final set, compared to previous sets:

Player            Ret InPlay%  UFE/Pt    FH%  
Alexander Zverev         6.7%    1.1%   1.0%  
Daniil Medvedev          3.9%   -3.2%  -1.2%  
Novak Djokovic           3.0%  -10.5%   1.5%  
Hubert Hurkacz           2.9%   -1.7%   0.3%  
Carlos Alcaraz           2.7%  -10.4%  -1.9%  
-- Average --            2.5%   -2.4%  -0.3%  
Jannik Sinner           -1.2%    0.1%   0.4%

Zverev, as we might have guessed, gets a lot of deciding-set returns in play. He's exceedingly conservative by every other measure we've seen, so why not here? Behind him, heading the non-pusher category, is Medvedev, who gets nearly 4% more returns in play in the final set that he did up to that point.

Unlike Zverev, the Russian also stays in control throughout the rally. He doesn't suddenly discover the otherworldly control of Djokovic and Alcaraz, who somehow reduce their unforced error rates by 10% in the deciding set, but he leads the rest of the pack, cutting down his mistakes by more than the tour average.

The third metric shown here--forehands as a percentage of all groundstrokes--is simply a curiosity. There's no right or wrong way to choose strokes, at least not at the level of the whole tour. As we saw last week, Medvedev and Zverev go for backhands on the plus-one shot more than anyone else, because they are in the unusual position that it might really be their stronger option. If a player improves his ground game in the fifth set--and this is nothing more than a hypothesis--it might show up in the numbers as more shots from his preferred wing. None of these men show a dramatic shift in shot selection, but I can't help but notice that Medvedev hits a few more backhands in the final set than he did in the two of four sets it took to get there.

If Medvedev reaches a fifth set in tomorrow's semi-final against Zverev, he won't need this level of savvy to know what's going on. The German's tactics, whether by design or instinct, are abundantly clear. Zverev can turn a shootout into a war of attrition, with two fifth-set tiebreaks already in Melbourne and an astonishing record of 22 deciding sets won in his last 26 attempts. While it will doubtless be a grind, the Russian might just be able to use his opponent's passivity against him. Faced with the tiny margins of a grand slam fifth set, every edge is worth exploiting.

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