How Long Does Return Quality Matter?

A deep return is better than a shallow one. A return to a corner is better than one down the middle. There’s no doubt that return placement matters, but how long does it matter?

With every shot after the return, it is logical that the effect of the return would decay. A strong return might not go for a winner, but it probably induces a weak reply, making it more likely that the returner can end the point on her next shot. But if she doesn’t, if the rally continues to 6, 10, or more shots, at some point the quality of that return is no longer a factor. Either she sacrificed the advantage it gave her, or her opponent defied the odds to get back on neutral (or better) terms.

You guessed it: We can quantify this.

Drawing on the thousands of 2020s matches logged by the Match Charting Project, let’s start with the simplest comparison: serves that landed beyond the service line versus those that landed in the service box. Deeper is unquestionably better: For men, a back-half return means winning the point 50% of the time, while an in-the-box return is good for only 41.4%. Even controlling for match (opponent, surface, etc), the difference is 7.7 percentage points.

Most of that advantage shows up in just a few shots after the return. These plots show the percentage-point advantage of a deeper serve at each stage of a rally:

Return depth matters more, and for longer, in the men’s game. A back-half return against a first serve is worth about 2.5 percentage points more to men than to women. Against first and second serves, return depth plays a role up to at least the eighth shot.

For women, this basic measure of return depth loses half of its predictive power once the rally reaches its fourth shot. By then, the server has either capitalized and ended the point, or she has squandered her advantage. (Or the return was good enough that she didn’t have an advantage to squander.) By the sixth shot the return is barely a factor at all: The confidence interval says the effect could be zero.

The server’s natural control of the point also explains the stair-step nature of the graph. A big part of the difference between return influence on 3-shot rallies and 4-shot rallies is that the points with the weakest returns become third-shot (plus-one) winners. There is no fourth shot. The effect is similar, if smaller, between the 5th and 6th shots as well, in some of the plots.

What about angles?

An ideal return forces the server to move away from the middle of the baseline. Intuitively, it seems like line-kissing returns affect the development of a point differently than deep ones do. To overgeneralize: If the server has to move, he could immediately be at a disadvantage. A deep serve, by contrast, merely stops him from putting the point away.

The next set of plots show the difference between down-the-middle returns and crosscourt returns. (That is, crosscourt to the ~third of the court closest to the opposite sideline.) For men, the difference between crosscourt and middle isn’t as great as the gap between back-half and front-half. For women, it’s about the same. The return still remains a factor until the sixth or seventh shot:

(Ignore the women’s trend lines that head back upward for long rallies. That might be a selection effect. Maybe returners who neutralize the server’s advantage are more likely to come out ahead in marathon points.)

Down-the-line returns are a little different. The biggest effect of hitting in that direction is an increase in service winners: In the next set of plots, check out the diamonds in the 2* column for second serves. That column includes all non-ace points; the other data points on the graph depend on the server putting a second ball in play:

I expected that crosscourt returns would both be better than down-the-line returns and have a longer-lasting influence. I was wrong about the first. All else equal, down-the-line returns are a bit more effective, assuming they land in. Maybe servers expect a crosscourt return and lean that way. There’s a stronger case for the second. The advantage of a down-the-line return is gone for women by the sixth shot of the rally, the seventh shot for men.

Finding the backhand

Often, the returner’s goal isn’t to hit a particular corner, it is to target the server’s weaker side. For men, especially, that side is usually the backhand. Maybe there’s a detectable advantage–and ensuing influence–in finding the server’s backhand?

The evidence says: Not really. On men’s first serves, a little bit, and it’s gone after another stroke or two. The plots tell the story:

Of course, tennis is complicated and these are descriptive statistics, not recommendations. Returners have to weigh several factors (assuming they have time to think at all), not just which wing to target. If men tried to hit more returns to the backhand side, they’d have to do so with opportunities that aren’t as well-suited to a return in that direction, and that next marginal percentage point of returns-to-the-backhand might not be as good. In that sense, seeing near-equal outcomes for returns to either wing suggests that returners have found a reasonable, if not quite optimal, balance.

What about the extremes?

So far, we’ve been looking at one variable at a time. What’s the difference between a really well-placed return and a poor one? To put it another way, how much does return location matter at the extremes, and how long does the difference persist?

We can measure that by comparing “shallow-middle” (service box, middle third of the court) with “deep-corner” (back quarter of the court, outer thirds of the court) returns. The difference is substantial–nearly 20 points of win percentage for men on both first and second serves–but it doesn’t last much, if any, longer than the other effects we’ve seen:

For women, the advantage of a very well-placed return is almost entirely gone before the sixth shot of the rally. It lasts longer for men, with the confidence interval touching zero only on the ninth shot. Still, both server and return have just a short window in which to capitalize on a weak or strong return.

Putting it all together: A good or bad return affects the development of the rally even after more shots have been struck. But not forever: If somebody tells you that a return set up a winner on the 12th stroke of a rally, they’re overstating the case. A good service return can accomplish a lot, but its powers are not unlimited.

Do Groundstrokes Break Down?

The human brain is a trend-spotting machine. A couple of groundstroke errors in a row, and fans and commentators conclude that a player’s stroke has gone off the rails, perhaps because her opponent has exerted just the right pressure. Shots, we say, can “break down,” and even that opponents can “break them down.”

Except… an awful lot of the trends we spot are mirages, misguided attempts to make sense of noisy data. Yesterday, we learned that first serves aren’t streaky. For pros, missing one doesn’t make it more likely that you’ll miss the next; women even tend to make slightly more first serves after misses. So, what about groundstrokes?

It’s a trickier phenomenon to pin down, because unlike first serves, forehands (or backhands) are not all created alike. After missing one forehand, you might not see one on the next point or two. Or if you do, it could be at a different angle, a different height, a different court position, and so on. Still–and long-time readers are going to struggle to believe me on this–there is a detectable effect! Really!

Based on women’s matches since 2020 logged by the Match Charting Project, if a player makes a forehand unforced error on one point, she is 0.45 percentage points more likely to make a forehand unforced error on her next point with a forehand in it. It’s a tiny shift, representing about a 2% tick upward from the typical error rate around 20%, but it is real. The results are about the same (slightly weaker, but in the same neighborhood) for backhands. Men are in the same neighborhood, as well.

But wait: If we control for set, establishing our expected error rates for a single set rather than the entire match, the effect shrinks, and for men, it vanishes almost entirely.

This is good news and bad news. There’s little or no short-term influence of one error on the next opportunity to hit that shot. But error rates do drift over the course of the match.

Drift away

Splitting matches into chunks of 20 forehand points, error rates move around quite a bit more than that sub-half-point shift. Without controlling for set, the typical WTAer sees her forehand UFE rate jump around 1.4 percentage points more than would be expected from chance alone. That’s still not detectable within a single match, but it is a meaningful difference in the long run. Over the last 52 weeks, the range in UFE rate between the most error-prone player (Anna Kalinskaya) and the least (Belinda Bencic) is only 9 percentage points. 1.4 points represents a jump of several places at most positions on the leaderboard.

A bunch of subsequent tests reveal some aspects of that drift. For one thing, it’s usually not a single stroke that ebbs and surges. When a player starts making more errors, both wings suffer. There’s a hint in the men’s data that forehand and backhand error rates don’t quite move in lockstep, but the data is inconclusive.

It’s also clear that players seize on their opponents’ sloppiness. You can probably imagine situations where gaffes seem contagious and no one can keep the ball in the court, but typically, one player tightens up his (or her) game while the other one struggles. I don’t know which direction the causation points: Does one player “break down” the other? Does she take advantage of her opponent’s errors and play more conservatively? Anything along those lines is just speculation at this point.

The strongest effects, though, were somewhere I didn’t intend to look. Error rates shift chronologically, both across sets and within them, in predictable ways.

Tightening up

These graphs show the trend in relative unforced error rates by set, for both men and women:

On both wings, players make more errors in the first set. Women improve their forehand error rate by almost a full percentage point between the first and second sets. While there’s not much movement after the second set, the rates stay well below the first-set standard.

Before we speculate about the causes, let me show you another pair of plots, now comparing relative error rates within sets, by pairs of games:

Again, we start high then tack lower. Though it’s not an unequivocal downward trend, the first two games are consistently the most error-prone, and tiebreaks are the least. (Players become more conservative in tiebreaks by just about every possible metric, from serve speed to rally length to errors.)

Combine those two effects, and you have some sloppy opening games. Here’s one more plot, using WTA data, showing each set broken into chunks of 10 forehand points. The top left corner is the beginning of the first set; the bottom right is the end of the third. Red means more errors than expected (the numbers are percentage points), blue means less:

Every set tightens up as it goes along, but my oh my are those first ten points brutal. These shifts account for much of the “drift” within matches. Error rates move for reasons other than chronology, but chronology is a single factor that seems to affect a large number of players.

Sloppy or aggressive?

High error rates are not inherently bad: Jelena Ostapenko has made a career out of winning matches when she loses one of three points with a (wild) miss. The trick is to pair errors with winners, to take the good aggression with the bad.

That’s not what’s happening here! For women, on both wings, winner rates are at their lowest in the first set. Within sets, winner rates are lower in the first two games than they are until 5-5, when tiebreak caution starts to take over.

These numbers strongly point toward a “warm-up” effect at the beginning of the match and a smaller “re-set” effect at the start of each subsequent set. Maybe that’s understandable: No amount of actual warming up can prepare you for the reality of a new opponent’s individual mix of speed, spin, and angles. And despite the dark red of that upper-left-hand heatmap cell, we’re still only talking about a shift of one percentage point: Enough to pick up across 4,000 charted matches, but far too small to notice even in a fortnight of attentive tennis-watching.

What about the players?

Up to this point, we’ve been talking about averages. We don’t have enough data to identify tendencies for most players, but we can find some.

One of the strongest individual-player findings for women is that Coco Gauff’s error rates drift quite a bit within a match: about three percentage points compared to less than two for the average player. Gauff is slightly more prone than average to a sloppy start, as well, but the full-match metric excludes the first 20 baseline points, so her variance goes far beyond that.

By contrast, Aryna Sabalenka and Iga Swiatek are remarkably steady, showing effectively no in-match variation in error rates beyond what would be expected from chance.

Sabalenka also stands out in that her aggression (winners plus errors) goes up under pressure, defined as the ninth game of a set or later, with the score within one game. The effect is small–a bit more than one percentage point–but it is striking because the average trend under pressure is negative. Gauff, Elena Rybakina, and Jessica Pegula all score about one percentage point in the opposite direction, more conservative under pressure than the average player. Iga is almost precisely average.

I haven’t said much in this post about men, because the trends are generally the same across both tours. Still, there are some interesting individual numbers for ATPers.

Both Stefanos Tsitsipas and Grigor Dimitrov see even more error-rate drift within a match than Gauff. Lorenzo Musetti is the slowest starter, committing the most errors (relative to match averages) in his first 20 chances per match of all men for whom I have a lot of data. It’s suggestive, though hardly conclusive, that those three outliers all have one-handed backhands. I can sympathize: If I play a match on Monday morning, my backhand starts rounding into form on Wednesday afternoon. (Tsitsipas and Dimitrov, for what it’s worth, aren’t slow starters; their error-rate drift comes later.)

A slow start isn’t necessarily bad. Second on that list behind Musetti is Carlos Alcaraz, even though Carlitos scores about average for general within-match drift.

Jannik Sinner’s career of bloodless executions turns up in the data as well. His within-match drift is the lowest (tied with Felix Auger-Aliassime, surprisingly enough) of all players with enough data. In the big moments, he grinds you down, committing fewer errors under pressure and improving his winner-errors ratio. He isn’t the most conservative in the big moments, though: That honor belongs to Novak Djokovic, with the perpetually cautious Alexander Zverev right behind him.

Circling back to where we started: Pro groundstrokes don’t really break down. They take a few games to reach optimal form, and on occasion, they rattle a bit. Most of the apparent trends we spot as fans are fake. But in this case, there are indeed a few drops of water in the desert of statistical noise.

The Point After a Second Serve

Here’s a hypothesis for you: First serves are streaky.

It seems unquestionably true for amateurs. Our serves start clicking, or more commonly, fall apart entirely. Pros, though, are built different. After untold thousands of serves in practice, they should be steadier. The question, then, is whether they exhibit any streakiness at all, whether one missed first serve makes it more likely that they’ll miss the next one as well.

We can test this with the ever-growing dataset that is the Match Charting Project. Across over 4,000 charted men’s matches since 2020, the effect of one missed first serve on the next first serve is basically … zero. Not exactly: Men might be very (very) slightly anti-streaky, meaning that they are more likely to land a first serve on a point after a first-serve miss. But the effect is indistinguishable from zero, and the natural yo-yo of alternating deuce and ad courts erases anything that’s left. Some players have different results on the deuce and ad sides, so they are more likely to “recover” from a miss simply because they get to switch back to their preferred serve direction.

A few individual men show up as more streaky (or resilient, to use a more pleasant if less precise term for “anti-streaky”) than the norm. In the 2020s data, Novak Djokovic comes out as one of the most streaky, while Carlos Alcaraz scores among those at the other end of the spectrum. The magnitude, though, is tiny: We’re looking at shifts of about one percentage point in first-serve-in rate after a missed first serve. There’s not even enough data to be sure there’s an effect at all. Even if there is, that one percentage point translates to about one extra missed (or made) first serve every four matches, on average. It’s certainly not something you could detect by watching a match, or even a full tournament.

The story is somewhat different for women. Again using Match Charting Project data from the 2020s, spanning another 4,000-plus matches, we find that women make more first serves than expected on the point after they miss one. “Resilient” or “anti-streaky,” it doesn’t hold for every single player, but it’s a clear trend across the tour. As with the men, deuce/ad explains some of it, about one-fifth of the overall effect. What about the rest?

It would be one thing if there was simply no streakiness: We could give credit to the players for having trained themselves to the point that they are human ball machines. Maybe there’s something psychological, where players see a mistake, make adjustments, and temporarily become even better servers than their typical selves. More likely, though, it’s tactical. My instinct is that the average woman’s first-serve rate goes up because, having just missed a first serve, she becomes more conservative.

The evidence supports my guess. On first-serve points after a first-serve miss, women win 0.3 to 0.4 percentage points less often, compared to other first-serve points within the match. It’s possible that the additional lost points don’t stem directly from serve tactics, but the persistence of the effect points strongly in that direction.

We can even be a bit more specific. The difference is not speed: I checked the first-serve speeds after first-serve misses from Wimbledon and the US Open between 2021 and 2024. Controlling for serve direction, women served just as hard on those follow-up points, possibly even a tiny bit harder. If the point-outcome data can be trusted, the conservatism comes from serve placement, not direction (wide/body/T) or speed.

The net effect of all this is basically neutral. It’s good to decrease the odds of another second serve, but a slightly weaker first serve reverses some of that benefit. After missing a first serve, women servers win points at about the usual rate.

Double faults

Everything we’ve seen so far is a tiny effect, and it’s virtually no effect for men. The psychological or tactical shift is a bit clearer when we shift from missed first serves to double faults.

After a double fault, both genders dial things back with their next first serve. Men drop about 0.25mph from their average first serve. Roughly half of that comes from picking safer targets: They are less likely to fire one down the T, where margins are smaller. Women show a much bigger effect, dropping just over 1mph from their first serve. More than half of that comes from the direction. They, too, opt for body or wide serves as they seek to get things back on track.

Here, the results are far from neutral. There’s some degree of momentum regardless of which serves go in. Both men and women are a bit more likely to win a point after winning the previous point. But a double fault is recognizably different than a point lost by other means. The average woman’s first-serve winning percentage drops by almost a full point after a double fault, compared to other ways they could have lost the previous point. A couple of studies of mine suggest that 1mph in serve speed will move first-serve win percentage between 0.2% and 0.5%. So serve speed explains part of the win-percentage drop after double faults; other manifestations of serve caution, like placement, may account for the rest.

The men’s serve-speed drop is much smaller, so it’s no surprise that the point-result effect is smaller as well. The data doesn’t allow us to be as confident about this one as a real effect, as opposed to just suggestively-oriented noise.

My initial hypothesis was wrong, but the investigation turned up some momentum (and anti-momentum) effects that are worth more attention. Should players try to keep their first-serve risk level steady, or is a conservative offering a good way to get back on track? Is it possible to go wide or to the body without giving up quite so much? Should returners lean more in that direction, knowing that a double fault could influence the next serve? Beats me!

Do Pushers Grow Out Of It?

Is Victoria Mboko a pusher? I was tagged in a Twitter exchange the other day debating that exact question. From watching her play, I would hardly compare her to Ostapenko, but the p-word wouldn’t have come to mind.

Rally Aggression Score puts her at +6, on a scale designed to run from -100 to +100. Based on 27 charted matches from the last 52 weeks, that makes her about neutral, tactically similar (at least along this dimension) to the likes of Belinda Bencic and Karolina Muchova. Counterpunchers, maybe, not pushers.

On the other hand, “neutral” overstates it. Lowell West devised the metric about a decade ago, and the game has changed since then. The way I initially scaled it, Petra Kvitova flirted with triple digits, and that was about it. Now, Dayana Yastremska gets close to 200. Elena Rybakina, at exactly 100 in the last year, ranks only fifth among players with at least five charted matches. There’s nothing so extreme at the other end: Emma Navarro has averaged -68, while the most passive top-tenners are Coco Gauff and Mirra Andreeva at -20 and -30, respectively.

Mboko’s +6, while hardly vintage Wilander, is indeed more passive than the average WTA player in 2026.

Aggressive growth

Will the Canadian change tactics with age? These days, it seems like nearly everyone at least tries to take more chances and hit more winners. (If you don’t, your opponent will!)

I can’t tell Mboko’s future, but I can load up a database and run queries on it.

So, different question: Do players in general change tactics with age? It’s easy to think of examples: Serena Williams got more aggressive over the years. Ostapenko (remarkably) has done the same. I’m not sure there are equally prominent players who have moved in the other direction, but it does seem like some teenagers show up bashing balls, then settle for a more measured game in their 20s.

I took all women with at least 20 charted matches, grouped their rally scores by year, and figured out how much each year’s score differed from their career norms. Average those deviations across all players, and this is what you get:

From age 18 to 36–the entirety of most players’ careers–there’s nothing to see here. Plus or minus five points of rally aggression score is a rounding error, especially since these are non-random samples based on what Match Charting Project contributors wanted to chart and could find on video.

The spike at age 37 is also not very instructive: It’s basically Serena Williams, and we already knew that as she aged, she took increasingly few prisoners. From 2007 to 2009, her average aggression score was about +20. In 2019, when she was 37, it was +109.

Still, that climb at the left end of the graph is suggestive. It doesn’t literally apply to Mboko, who is already 19. But it supports a plausible narrative. When young women–especially the youngest prospects–arrive on tour, they aren’t as strong, or perhaps even as tall, as they will soon become. (Even Lilli Tagger recently gained a centimeter.) Their experience is disproportionately against juniors, who are even less physically imposing, relative to adult pros. The typical 16-year-old, no matter how talented, isn’t going to show up on tour and play like Sabalenka.

There are exceptions, of course. Maria Sharapova’s highest single-season aggression score was in 2004, when she was 17. Madison Keys arrived on the circuit playing essentially the same game she would play for the next decade. Iga Swiatek was more aggressive at age 18 than she has been since.

On average, though, the youngest players are more conservative–fewer winners, fewer errors–than they will become as they graduate from their teens. The mechanism could well apply to a 19-year-old, too.

The trend is null

We’re always talking about how players could develop and improve, or what their new coach brings to the table. Yet the undefeated champion of tennis forecasting is the null hypothesis. The null hypothesis, of course, means that you should’ve skipped this entire post and watched a Friends rerun instead.

It is boring, but the best way to predict how a player will look next year is to point at their current results and say, “yeah, just like that.” You can fiddle around the edges and maybe find players on the cusp of something or other, but … no, usually you can’t even do that.

Here are the year-to-year aggression trends of the women with the most matches in the MCP database:

See that trendline that goes from the lower-left corner up to the upper-right? No, you don’t, because it’s not there. The closest is Serena, who dipped to +12 in her late 20s before getting hyper-aggressive in her 30s.

To answer the question posed by my headline, then: No, pushers don’t grow out of it. The style of play you see today is a good predictor of the style of play you’ll see a decade from now.

Lucky for Mboko, then, that she isn’t a pusher. Throughout her career, I’ll bet she tries a lot of new things and incorporates plenty of fresh ideas from a handful of high-profile coaches. The end result may well take her to the top of the rankings: A 19-year-old ranked 6th on the Elo table has a bright future ahead. If she finds a game that takes her all the way to the top, odds are it will look a lot like what we’ve seen so far.

What Does Felix Auger-Aliassime Do So Right On Indoor Hard Courts?

Felix Auger-Aliassime has earned a reputation as a world-beater on indoor hard courts. He’s no Jannik Sinner–as Sinner reminded him all four times they met last year, twice indoors–but FAA is a fearsome customer against just about anybody else.

Last week the Canadian added to his indoor title haul with his second-straight championship in Montpellier. This time, he straight-setted Adrian Mannarino. While that win doesn’t particularly raise any eyebrows, the body of work keeps growing. It’s his eighth career title indoors, three of them at ATP 500s. Last fall in Paris, he also reached his second Masters final. (The first was in Madrid, the indoorsiest of the clay Masters.)

What’s the secret?

The conventional wisdom is that he has a big game, especially a deadly first serve. The controlled environment indoors, plus typically fast conditions, play to his strengths. The serves skid across the court even faster. His weaknesses are mitigated because the bounce is more predictable and because points are shorter.

All that sounds plausible. My only gripe is, couldn’t you say that about a lot of players? The whole paragraph applies, almost word for word, to Hubert Hurkacz, who has two Masters crowns on outdoor hard, plus a clay title, yet just a pair of indoor 250-level championships. What about Matteo Berrettini? The description might match him even better, yet the Italian has never won a title indoors. He has reached only one indoor 250-level final.

Before we go to the numbers, let me give you my seat-of-the-pants theory. FAA has huge weapons, but he doesn’t always play like it. He doesn’t consistently swat away easy plus-ones like Berrettini does. He gets sucked into long rallies, where he’s often at the disadvantage. Indoors, though, he knows what the tactics are, and he plays the way he should play. Indoor Felix, then, is the best Felix, both because his game is suited to the conditions and because he shows up with the right approach.

On the other hand, the last two points against Mannarino on Sunday were 8- and 18-shot rallies, respectively. So, you know, don’t trust my pants.

Numbers!

You can, however, trust the spreadsheets. The Match Charting Project has well over 100 Auger-Aliassime matches. Going back to 2020, the total includes 41 on indoor hard and 40 on outdoor hard, nicely suited for some comparisons. I was tempted to throw out the seven Tour Finals matches from the indoor tallies, because they skew the quality of the opponents, but the Canadian’s indoor averages are about the same with or without them.

Start with serve stats:

Surface       Unret%  <=3 W%  RiP W%  
Indoor Hard    35.7%   47.7%   55.5%  
Outdoor Hard   32.8%   43.4%   49.7%

About three percentage points more serves don't come back, and there's an even wider gap in points polished off on the serve or plus-one (the "<=3 W%" stat). The biggest gap here is in points won when the return comes back. Sub-50% is below average, especially for hard courts. 55% or better is very good, even in fast conditions.

Almost all of the indoor/outdoor serve differences are thanks to the first serve. FAA's second-serve numbers are about the same regardless of roof status.

Of course, Felix isn't the only guy on tour who wins more easy serve points indoors. I don't have comprehensive stats on the indoor/outdoor split, so I can't tell you the exact tour average. But we can compare how much Auger-Aliassime gains on serve to how much he gives up on return:

Surface        RiP%  RiP W%  
Indoor Hard   65.3%   48.8%  
Outdoor Hard  67.5%   43.2%

He retrieves 2.2 percentage points fewer serves indoors--better than the 2.9-percentage-point difference he gains on serve. But when he gets the serve back, he's actually better indoors than outdoors! He gains five percentage points in that department on serve, and he gains the same margin on return.

This might dovetail with the conventional wisdom. His monster serve really pays off indoors. And predictable conditions give him a bit of cover on return.

Whatever the reason, Auger-Aliassime's groundstrokes are way more effective indoors. My Potency metrics, FHP and BHP, combine winners, unforced errors, and shots that set up winners and errors. They give you one-number estimates of how valuable each shot is, and... wow:

Surface       RallyLen  FHP/100  BHP/100  
Indoor Hard        3.7     +8.5     +0.0  
Outdoor Hard       3.9     +3.2     -5.8

His indoor points are a little shorter, but I assume that is typical. I would've guessed that the difference was greater.

The Potency numbers (expressed here as rates per 100 shots), tell a more emphatic story. A +3.2 FHP/100 is ok, not great. Tommy Paul and Ugo Humbert are in that zone. On the other hand, +8.5 is the 52-week average of Carlos Alcaraz. A -5.8 BHP/100 is near the bottom of the pack, below the likes of Ben Shelton and Grigor Dimitrov. By contrast, +0.0 is, as it sounds, a good solid average.

These numbers don't drill into the "why" questions that naturally follow. But they help us pick between theories. I suspect that much of the difference in groundstroke stats has to do with the shots he gets to hit. The winners are downstream of good serves. Auger-Aliassime picks up some aces, but he picks up more plus-one (or even plus-two) winners, and those make his forehand and backhand numbers look good.

The "indoor predictability" thesis also looks good here. Remember that everybody should benefit from that--and not everybody's numbers improve like Felix's do--but it may be that the Canadian is more-than-typically exposed by the vagaries of outdoor play.

All the angles

Quick thought experiment. Picture Roger Federer hitting an ace.

Now imagine Auger-Aliassime hitting an ace.

What specific serves came to mind? If you're like me, you pictured Federer shooting a bullet right down the tee. And then you visualized FAA hitting a flat bomb out wide.

Of course, both guys hit plenty of aces in every direction. The charting stats suggest that Felix has a slightly better chance of an ace when he goes up the middle. (Federer did too, by a bigger margin, as do most players.) Still, this indoor/outdoor split caught my eye:

Surface       Deuce Wide%  Ad Wide%  BP Wide%  
Indoor Hard         50.5%     47.8%     33.7%  
Outdoor Hard        46.9%     45.2%     41.0%

Each column shows how often Auger-Aliassime opted for a wide serve in various scenarios. The first-serve differences are probably more marked, because his second-serve tendencies are about the same.

Indoor, he goes wide more often--but less often under the pressure of break point. While the margins are rather slim, it seems like the wide serve becomes his bread-and-butter indoors, and he uses the tee serve to mix things up on break point--because he's hitting more wide serves the rest of the time.

Wide serves are more likely to come back, but they don't make the returner any more likely to win the point. Especially against Felix: His signature serve might not even be an ace, but a wide bomb that the returner just barely plops back over the net.

The fact that he hits more wide serves indoors explains a lot. He gets a few more unreturned serves (as everybody does, probably), but he gains more of an advantage on the serves that (weakly, oh so weakly) come back. His groundstroke stats sparkle, padded by those easy balls.

Here's one final comparison:

Surface       2ndAgg  
Indoor Hard       +7  
Outdoor Hard     +46

"2ndAgg" is the Aggression Score stat tailored specifically to second serves. A higher score means more double faults and more unreturned second serves. Lower means fewer risks on second balls. +7 is quite conservative: Only about a dozen players consistently score so low.

But--those careful second servers include Sinner, Hurkacz, and Berrettini. With a game like Auger-Aliassime's, the second serve isn't the time to take risks. And indeed, in all of his indoor finals, he has never topped a double-fault rate of 5%. In the Montpellier final, he missed his second serve just once, and he committed no double faults at all in the quarter- and semi-finals.

Here, finally, is some support of my seat-of-the-pants theory, that when Felix goes indoors, he plays the way he ought to be playing all the time. He stays within himself, which is still imposing enough to earn a lot of cheap points. It's not a particularly complicated story, and I'm still not convinced why it doesn't apply to a half-dozen other guys on tour. Maybe it is all about the wide serve, the signature shot that allows Auger-Aliassime to manage risk and put his opponents on the back foot, all at the same time.

Defanging the Ball Bashers With Sara Bejlek

On Saturday, 20-year Sara Bejlek won her biggest title–by far. She had just slipped out of the top 100, so after qualifying for the main draw in Abu Dhabi, she charged past the likes of Jelena Ostapenko and Clara Tauson, then secured the trophy with a 7-6, 6-1 win over almost-top-tenner Ekaterina Alexandrova.

It’s tough to overstate just how out of the blue this was for the Czech. By ranking, Ostapenko, Tauson, and Alexandrova represent three of her four highest-ranked victories. Her two other main-draw victims, Sonay Kartal and Ashlyn Krueger, also count among her top ten. And she beat Kartal 6-0, 6-2.

That’s a big-hitting set of opponents. Bejlek, by contrast, lacks the power weapons that are becoming standard on the WTA tour. As a left-hander, she practically begs us to call her “crafty.” One upset against that group is plausible enough: After all, Ostapenko’s low-percentage tennis invites chalk-defying outcomes. But so many?

The final

I don’t pretend to be an expert on the Czech’s game. She has only a couple dozen tour-level matches under her belt, so she’s a newcomer for most of us. That said, we now have a detailed match chart from Saturday’s final that offers some clues as to how Bejlek battled the barrage of ball-bashers in Bahrain Abu Dhabi.

The conditions helped. It was windy, and the conditions were slow. None of that favored Alexandrova, who likes predictable balls she can smack flat back across the net. The court speed not only made it difficult for Alexandrova to hit through the court, it gave her a little less pace to work with on Bejlek’s own balls. Surely the Russian must have wished she had played indoors in Ostrava(!!!) instead.

The lefty’s game plan seized on those advantages. She looped balls back down the middle. She sliced more than she had to, refusing to give her opponent a predictable bounce height. She mixed in some almost impossibly slow serves. She won the first point of the match with a dropshot-lob combo that, while she didn’t attempt many more, surely gave Alexandrova pause.

The central result was that the Russian just couldn’t hit winners. By my count, she ended with 13 winners against 37 unforced errors. Just as telling as the abysmal ratio was that the 13 winners represented less than 10% of total points. In her last 60 charted matches–going back to 2022–opponents have held her under 10% just six times. When they do, it’s usually because they take the racket out of her hands by playing hyper-aggressively themselves. Two of the opponents in question were Anisimova and Yastremska.

Bejlek, by contrast, gave Alexandrova ball after ball that looked like it should have been obliterated. In different conditions, or when the Russian was in better form, maybe the winner count would have been much higher. But from the first few games, it was clear that the Russian wasn’t confident in her ability to take control. Big, aggressive hitters usually have more influence on rally length than more passive opponents, but that wasn’t what happened on Saturday. The average point lasted 5.1 strokes, tied for third-longest among the nearly 100 charts we have from Alexandrova’s career.

Translated into tennis cliché: Bejlek let her opponent beat herself.

If we can extract one concrete skill from the Abu Dhabi final, it’s that Bejlek doesn’t let servers overpower her. 85% of Alexandrova’s serves came back, compared to a 52-week average of 75%. Again, we don’t have much data yet on Bejlek, but here’s another bit of evidence: In Madrid two years ago, she retrieved more than 80% of Rybakina’s serves. The Aussie Open champ is the toughest on tour to return, usually holding opponents to around 67%.

Despite all the frustrations and all the extra shots she had to hit, Alexandrova nearly pulled out the first-set tiebreak. She led 4-2 at the change of ends before getting dragged into a series of long rallies broken up only by a couple of well-executed short points from the Czech. Having dropped the 95-point slog that was the first frame, Alexandrova ran out of ideas. She simply watched the error count soar.

You don’t win slams by letting opponents beat themselves–marathon runners notwithstanding. But in the hands of someone persistent enough, it’s a game plan that can keep you in Bejlek’s new neighborhood of the top 40. With 500 points on the books from Abu Dhabi, the left-hander has the rest of the season to prove that she belongs.

Carlos Alcaraz Will Return Your Serve. Good Luck With That.

It often feels fruitless to pick out the strongest aspects of the Carlos Alcaraz game. (Sinner’s, too, of course.) He is so good at everything that we tend to focus on the same few particularly attention-grabbing attributes. The knee-buckling dropshot, the outrageous will to win (and corresponding fifth-set record), the forehands at full stretch.

We don’t ask often enough why Alcaraz or Sinner won a match, because it seems obvious. They’re simply better than everybody else, except for maybe Novak Djokovic or Cameron Norrie on a good day.

And it’s true, there’s no single reason why. (There’s never a single reason for anybody, though most players make it easier to isolate a small number of effective shots or tactics.) All we can do is focus on one part of the Alcaraz game, then goggle at it.

Today, let’s goggle at the return of serve.

Here’s a fun place to start. Djokovic completed five matches at the Australian Open. Take a look at his first-serve win percentages from those five matches:

Opponent           1st W%  
Martinez            93.2%  
Maestrelli          86.0%  
van de Zandschulp   77.0%  
Sinner              71.4%  
Alcaraz             65.9%

Djokovic, at any age, is an outstanding hard-court server. 71.4% is below average: Sinner did a nice job on return, even if he forgot on some break points. 65.9%, though, is unreal. Of the ATP top 50, how many players do you think win fewer than 66% of their first-serve points? One: Sebastian Baez. Alcaraz turned Djokovic into Sebastian Baez.

It wasn’t a fluke, either. Djokovic won 66.1% of first-serve points against Alcaraz in the US Open semi-final last year. Those two aren’t the absolute worst serving performances of Djokovic’s last twelve months–Vacherot held him to 60.5% in Shanghai, and Musetti kept him to 61% in their abbreviated match–but they are close.

Two separate skills

Charting data allows us to break down service returns into two components:

  1. Getting serves back
  2. Winning points after getting the serve back

Pretty straightforward stuff. You want to get as many serves back as possible, but you also want to set yourself up to win points after you do.

There’s something of a tradeoff here. Jaume Munar is a good example of somebody who retrieves a ton of serves but loses a lot of the points because he doesn’t do enough with the return. Andrey Rublev is the opposite, not getting many returns back, but winning a relatively high percentage when he does. Adjusting for surfaces and opponent quality, the end result for Munar and Rublev is about the same, even if they get there via such different routes.

The tradeoffs don’t apply to everyone. Take a look at the scatterplot, which shows percentage of returns in play, and in-play return-points won, for all ATPers with at least ten charted matches in the last 52 weeks. The higher you are above the green regression line, the better. You can mouse over each dot for player details, but I don’t need to tell you whose dots are red:

ATP Returns in Play

10+ charted matches (last 52 weeks) • RiP% vs RiP Win%

Sinner & Alcaraz
Mere Mortals
Regression Line

Both halves of Sincaraz get more returns back than average, and they win more of those in-play points than anybody else.

(How they win the in-play points is itself a multifaceted question. Both Sinner and Alcaraz rank in the top six by my forehand and backhand potency metrics, and Alcaraz’s backhand rating continues to creep upwards. I also dug into their shot tolerance last year and found new statistical categories for them to lead.)

Remember I started out by talking about first-serve returns. That’s where Alcaraz really shines, even above his brother in world domination. Same idea, first-serve returns only:

ATP First-Serve Returns in Play

10+ charted matches (last 52 weeks) • 1st Serve RiP% vs RiP Win%

Sinner & Alcaraz
Mere Mortals
Regression Line

Alcaraz is the right-most red dot. There are 36 players on that plot, and Alcaraz gets more first serves back than all but four of them. (And he’s basically tied with Medvedev, the blue dot underneath his.) There’s no tradeoff for Carlitos: He gets more balls back than almost anybody, and he wins more of those points than anybody except for Arthur Fils (barely), Sinner (barely), and Rublev (whack!).

Both skills were on display in Sunday’s final. Alcaraz put an astonishing 76.5% of Djokovic’s first serves in play–almost off the right side of the scatterplot, against an elite opponent, on a hard court. I say “astonishing,” but was it even a surprise? At the US Open, Alcaraz got 75% of Novak’s first serves back.

When you can handle so many first serves, the win rate barely matters, but of course Carlitos did fine in that department as well, winning 44.6% of those in-play returns in Melbourne. Lower than his usual rate by a healthy margin, but hey, it was still Djokovic, and a massive number of in-play returns is always going to include a fair few weak ones.

When I started looking at returns in play about a decade ago, the tradeoff was clearer. More players fit the Munar or Rublev molds, getting a lot of serves back, or winning a high percentage of points when they did–but not both. Now, the relationship between the two stats is positive, but only slightly. They’re best understood as unrelated.

But for Alcaraz, tennis is built out of a dozen or so unrelated skills–all of which allow him to tower over the field. Sinner is close enough, and his serve might tilt the scale slightly in the other direction. Everybody else, though, is left scratching their collective head. Djokovic became the greatest of his generation by taking away opponents’ second serves. When Alcaraz neutralizes your first, what’s left?

The Rybakina Serves That Tipped the Scale In the Melbourne Final

In Saturday’s Australian Open final, Elena Rybakina won 92 points. Aryna Sabalenka won 92 points. Rybakina won 76% of her first serve points; Sabalenka won 75%. Both players held on to 48% of their seconds. Even their average first serve speeds were nearly identical, Rybakina’s 178 km/h nipping Sabalenka’s 177 km/h.

Only a few moments really mattered. Sabalenka converted two of eight break points. Rybakina converted three of six.

With such narrow margins, we should be cautious to draw conclusions about tactics and player skills. Flip one or two of those break opportunities, and it would have been a very different trophy ceremony. Anybody who tries to tell you “why” Rybakina won should keep that in mind. Still, Sabalenka would surely like to know how to secure another half-dozen points and put the result out of the range of luck. Rybakina will hope to do the same.

Pick target, hit target

Rybakina is the best server in the women’s game. Her ace rate over the last year is better than 10%–a percentage point ahead of second place (Osaka), and miles ahead of Sabalenka’s 6%. Rybakina has won nearly 75% of her first-serve points, while no one else cracks 73% and only a few players are on the north side of 70%.

At key moments on Saturday, Rybakina dazzled with her ad-court serves out wide. She saved the only two break points she faced in the first set with back-to-back unreturned serves, both wide. She finished the match with another signature delivery, acing Sabalenka out wide on match point.

If you’re looking for a “why,” it’s tempting to focus on those wide ad-court serves. Rybakina made 18 first serves when she aimed for that corner, and she won 14 of those points.

But! It’s not the ad-wide corner, specifically. Rybakina was even deadlier when she targeted Sabalenka’s backhand corner in the deuce court. She landed 14 of those first serves, winning 13.

Here’s the Rybakina method for defeating the world number one:

  1. Have a world-class serve
  2. Aim first serves at the backhand corner
  3. Make half of them

Easy, right?

Apparently not easy

Fair enough, most players don’t have anything like Rybakina’s serve. A few–Osaka, Noskova, Qinwen–can do a decent impression on a good day. Still, it’s an uphill battle to knock off Sabalenka with aggression from the line.

What’s striking, though, is that most opponents don’t really try.

Across 120+ charted matches since the beginning of 2024, Sabalenka’s opponents aimed their first serve at her backhand corner about 40% of the time. (That doesn’t mean they aimed 60% at the forehand corner: A fair number of first serves don’t land close to either corner.) In the vast majority of matches, her opponent aimed half or fewer of their first serves at her backhand corner.

On Saturday, Rybakina targeted the backhand corner 63% of the time.

The first serves that landed in were so devastating in part because she took a low-margin approach. Rybakina already misses more first serves than almost anyone on tour: Her 57.4% first-serve-in rate is worse than 45 of the top 50 women. Against Sabalenka, she succeeded exactly half the time when she fired in that direction. Corner-aimed serves are (unsurprisingly) lower-percentage for everybody, but her 50% was even worse than tour average.

It’s a smart tradeoff. Combine the two numbers, and we see that on 32% of her service points, Rybakina put a first serve in play to Sabalenka’s backhand corner. Those, as we’ve seen, are as close to guaranteed points won as you can find. Sure, that leaves 68% of service points to worry about. Yet as much as Rybakina’s premier weapon glitters, she’s a solid average at everything else. She’ll pick up a lot of those other points with quality second serves or rocket-powered firsts to the forehand corner, or by winning baseline rallies.

In the past two years, only a handful of players have managed to put first serves to Sabalenka’s backhand corner on as many as 32% of points. Even then, it doesn’t always work: Marketa Vondrousova, for instance, is unparalleled at hitting her targets, but her deliveries are softballs in comparison. For the players who can serve big, though, Rybakina may have pointed the way to tougher challenges against the world number one.

Ka-zam

This might be a recent refinement to Rybakina’s match tactics. We have over 80 charted matches for her since the beginning of 2024, and she has rarely aimed so many of her serves at the backhand corner. To be clear, she doesn’t need to. She straight-setted Sabalenka for the year-end title in November with only 44% of first serves pointed at that target.

But suggestively, Rybakina hit nearly as many first serves to the backhand corner in her Australian Open quarter-final match against Iga Swiatek. While she wasn’t quite as successful, landing just 40% of those attempts, the end result was encouraging. Even with all the misses, backhand-corner firsts accounted for a quarter of her service points. And she was as eye-poppingly successful on those points against Iga as she was in the final. Swiatek salvaged just 1 of 12.

It remains to be seen whether this is repeatable. When Rybakina is serving at her best, peppering the backhand corner is probably a good way to take advantage. (Unsurprisingly, since this is something tennis coaches tell twelve-year-olds.) If she’s misfiring, low-percentage first serves are probably not the way to fight her way through.

And surely, the world number one will start taking a few more backhand-return reps. She doesn’t have to turn into Andre Agassi to negate Rybakina’s new-found advantage. She just needs to defend that corner a little better. 94 or 95 points would have gotten the job done on Saturday. Even against a world-class serve and superb tactical execution, Sabalenka won 92. The two women will continue jostling for an edge, and it looks like the battle will increasingly take place with Sabalenka leaning to her left.

The Challenger Warrior Index (for Damian)

This post is dedicated to the memory of Damian Kust, tennis journalist and honorary Challenger warrior. He died this month at the age of 26.

Whatever it is that makes the Challenger tour compelling, it isn’t just the rising stars. Sure, when a Sinner or a Fonseca tears through the ranks, we tune in. Challenger-level competition is a litmus test, and we want to know whether the buzz is justified. But tomorrow’s all-world stars are just passing through. Fonseca played all of 56 matches at the level, and he’s already top-30. Sinner played 42. Federer played one.

If you’re the sort of person who is attracted to Challenger-level tennis, I suspect that the struggle is part of the appeal. Three-hour marathons, qualifying cuts, third-set cramps, tough losses to teenagers and aging veterans alike. We’re drawn to the sort of player who slogs away on Court 2 long after the rising-star top seed advances on Center.

Maybe this is something that can’t be quantified. But hey, what am I here for if not to stick numbers where they don’t belong?

Hence, the Challenger Warrior Index.

Challenger warriors are the guys who win matches the hard way. (If they could do it the easy way, I’m sure they would, but then they’d be playing bigger events.) The trick, when it comes to ranking “warrior-ness,” is to balance winning with fighting. The Index gives credit for victories and ranking improvements, yet it also boosts players for showing up often, especially when they push their opponents to the brink.

Here’s how it works. For the entire previous season, players get points for each of the following at Challengers and slam qualifying:

  • 3 points per match, plus 2 points for each match win;
  • 2 additional points for a three-setter, another 2 points if they win it;
  • 1 point for each tiebreak, an extra two points if it’s a deciding TB, a bonus three points if they win it;
  • 2 extra points per match that hits the three-hour mark;
  • 5 points for reaching a final, another 5 points per title;
  • 1 point per ranking place gained over the season, up to a maximum of 100;
  • 20 point bonus for a year-end ranking inside the top 100 (AO main draw!)

The various 3-set bonuses are doubled for five-set matches in slam qualifying.

I don’t claim that this is the final word: I tinkered, and I’m making it up as I go along. Like I said, this isn’t the sort of thing that is meant to be quantified. Your personal Index would probably weight things differently.

2025 warriors

Here are the official, indefatigable warriors of the 2025 Challenger tour:

CWI  Player                    Matches  Titles  Rkg Gain  
588  Francesco Maestrelli           72       3       103  
586  Eliot Spizzirri                65       2       139  
560  Emilio Nava                    67       4       124  
542  Liam Draxl                     66       1       114  
539  Joao Lucas Reis Da Silva       77       1       194  
520  Roman Andres Burruchaga        71       3        51  
519  Ignacio Buse                   64       2       132  
516  Marco Cecchinato               72       1       147  
510  Viktor Durasovic               58       1       176  
509  Juan Carlos Prado Angelo       70       1        78

Maestrelli and Spizzirri come out in a near tie. Fittingly, the Italian triumphs by virtue of playing a few more matches.

The points-weighting, however arbitrary, works out nicely, rewarding differently playing styles and surface preferences. Everyone near the top of the list enjoyed a significant ranking boost over the course of the year, partly because of the points it earns, and partly because ranking boosts tends to go hand-in-hand with playing and winning a lot of Challenger matches.

As if on cue, Maestrelli is delivering on his warrior status this week, with two victories so far in Melbourne qualies. Even more appropriately, Draxl has done the same, thanks to a third-set tiebreak victory over Vitaliy Sachko to finish today’s session.

Here is the CWI roll of honor, going back another decade:

Year  CWI  Player                   Matches  Titles  Rkg Gain  
2024  587  Tristan Boyer                 71       3       135  
2023  589  Facundo Diaz Acosta           66       4        96  
2022  603  Matteo Arnaldi                80       1       229  
2021  634  Benjamin Bonzi                69       6       101  
2020  357  Aslan Karatsev                38       2       177  
2019  583  James Duckworth               71       4       134  
2018  601  Cristian Garin                71       3       227  
2017  660  Blaz Kavcic                   75       2       120  
2016  590  Gerald Melzer                 66       4        98  
2015  632  Daniel Munoz De La Nava       70       3       131

Arnaldi’s 80-match campaign was an impressive effort, the last one to merit a Warrior Index over 600. But the overall champion is Blaz Kavcic. In 2017, he played a whopping 32 three-setters, winning an even more eye-popping 25 of them. Five of the third sets went to a tiebreak, and he won them all. While none of those matches crossed the three-hour mark (Marco Cecchinato was the 2017 champ in that category), there’s no doubt that Kavcic showed up ready for battle, all year long.

There are more ways to measure Challenger success than future fame and fortune. I hope the Warrior Index points at some of the reasons these players deserve our admiration, no matter what their career peak ranking turns out to be.

How Much Would a Second Forehand Be Worth?

Maybe you’ve seen the videos floating around of 13-year-old Lucas Herrera Sanchez, who hits a forehand on both sides:

The replies are fascinating. Responses run the gamut from “Why doesn’t everybody do this?” to “Switching grips will kill him.” Or my favorite: “What if he needs to hit a backhand?”

So we’re agreed: It could be the future of tennis, or it could be nothing. It isn’t completely unprecedented: Cheong-Eui Kim cracked the top 300 a decade ago, and a handful of juniors have reached an international standard for their age groups. Going way back, Beverly Baker Fleitz (#128 on my Tennis 128) took her two forehands all the way to the 1955 Wimbledon final. John Bromwich, another Wimbledon finalist, hit forehands and backhands from both sides.

And, of course, there’s a long history of teaching kids to hit forehands with their non-dominant hand. Rafael Nadal is a natural righty, while all-timers Maureen Connolly, Margaret Court, and Ken Rosewall were lefties who played right-handed. There’s no reason why any of those players couldn’t have developed two forehands instead of the one they did.

Let’s try to put some numbers on this. What’s the value of having two forehands instead of one?

Plug and play

We can’t run the counterfactual where, say, Carlos Alcaraz learns two forehands from age six. But we can work out what would happen if his backhand were exactly as effective as his forehand.

I probably don’t need to tell you that this would be an improvement for most players. We have ten-plus matches’ worth of 2025 charting-level data for 37 different men. Going by my Forehand Potency (FHP) and Backhand Potency (BHP) metrics, only three guys–Alejandro Davidovich Fokina, Daniil Medvedev, and Alexander Zverev–were more effective on the backhand side. Everybody else would’ve benefited from magically attaining forehand-level performance on both wings.

FHP and BHP tally up winners (plus forced errors), unforced errors, and shots that lead to one of those outcomes. Jannik Sinner, for instance, scores +13.2 FHP per match. Divide by 1.5 to translate to points, and Sinner’s forehand earned him about nine points per match more than a “neutral” forehand–one more like Zverev’s.

The typical tour regular grades out at 6.7 FHP and 0.6 BHP per match. That’s a difference of about six, or roughly four points. Put another way: Give the average player a backhand as effective as his forehand, and he’d win four more points per match.

Plus or minus

Four points per match. The average match runs about 140 points, so that’s a boost of nearly 3% of total points. Can you feel something dripping on you? That’s a tennis player uncontrollably salivating.

Three percentage points is huge. I once estimated that an improvement of one point in a thousand (0.1%, or one-thirtieth of 3%) was worth a single position in the rankings. That model wasn’t really designed to handle such big adjustments, so we can’t exactly say that a second forehand would be worth a 30-place ranking boost. On the other hand: Give, say, Tommy Paul four more points per match, and his point-winning rate would be as high as anyone except for Sinner. Hand the same boost to 49th-ranked Jenson Brooksby, and he’d win more points than anyone ranked outside the top six.

But. BUT. So many buts.

I don’t know about Herrera Sanchez, but I suspect that most two-forehanded players still have a weak side. Maybe the gap wouldn’t be as big as the standard forehand/backhand difference. But even with training from a young age, I doubt that the average unnatural-side forehand would be as strong as the player’s natural side forehand. I have no idea what that means for the 3% number, other than the fact that it is too high.

There’s also the issue of grip-changing. Depending on who you ask, the delay and awkwardness of switching from one forehand grip to the other either dooms the whole project, or it isn’t that big of a deal. I suspect that if a kid can learn to hit two forehands, he can figure out the grip-changing issues. Still, there is a probably a cost. (If nothing else, on return of serve. It might make sense to have a defensive backhand for first-serve returns only.) Again, I have no idea what that cost is. You give up a few more winners, but you hit better shots when you get there.

On the other other hand, simply plugging in forehand value for backhand value might in one regard understate the benefits of having two forehands! 53% of ATP groundstrokes are forehands, yet most players target their opponents’ backhands. In other words, pros are covering considerably more than half the court with their forehand. There’s a cost to that: Awkward inside-out attempts, suboptimal court position after the shot, etc. Depending on the player, I’d guess that 10% to 20% of forehands would be backhands if the forehand weren’t the better option. (For example, only 45% of Medvedev’s groundstrokes are forehands.)

The better a player’s secondary shot, whether a backhand or a weaker-hand forehand, the less often he’ll go out of position to hit a forehand. Those are some of the toughest forehands, so taking fewer of them will mean (dominant-hand) forehand potency will go up, too. As with the other complications, I have no idea how to quantify that with the data we have. It’s probably not a significant change to the number, but directionally, it mitigates some of the effect of second-forehand weakness and grip-changing.

Stepping back

While I can calculate the hypotheticals, this is ultimately a coaching and player-development question. Given a talented, motivated youngster, is it worth teaching them a second forehand instead of a backhand?

Here, I really have no clue. Maybe Herrera Sanchez will make it big. The same level of early tinkering certainly worked out for Rafa! But how often have coaches tried this? For every Rafa or Rosewall, are there ten kids who flamed out (or just gave up) early because a weaker-hand forehand was too frustrating? Or did they end up starting late with a proper backhand, never fully developing that shot? How many youngsters even have the potential to develop a powerful forehand with their non-dominant hand?

It’s hardly a magic bullet, even if a junior does manage to develop high-quality shots on both wings. While 3% of total points is huge by tennis standards, you still need 50% to win most matches. If an up-and-comer with two forehands tops out at 5-foot-9, or struggles too much with double faults, or doesn’t develop elite movement and anticipation, or comes up short on any one of a hundred more dimensions, he’ll have a hard time establishing himself on the Challenger tour, if that. “Not good enough” plus 3% is still, almost always, not good enough.

The best way to think about this, I think, is to frame the second forehand as a really, really good backhand. It isn’t exactly the same, but it’s close enough. Novak Djokovic has one, and of course it has worked out for him, because he’s historically great at all sorts of things. Benoit Paire had one: He won three titles and made an appearance inside the top 20. Elmer Møller has one, and at age 22 he’s still hunting for a top-100 debut. A non-dominant-side groundstroke of that caliber is an incredible asset, yet it’s still a small part of a winning formula.

Is developing a second forehand easier than doubling up on backhand-down-the-line drills? Are there more kids out there who could crush it with their non-dominant hand than could develop an absolute top-tier backhand? I don’t know! If Herrera Sanchez (or someone else) makes enough waves, more coaches will consider the possibilities. Then we’ll get more data, and we might be able to sort out whether two forehands is a blind alley, or if it really is the future of tennis.