Category: Rally statistics

If Carlos Alcaraz is the prince of the drop shot, Alexander Bublik is the court jester. We learned this week that Bublik hits droppers more than any other tour regular, about once every 14 points. That’s three times as often as tour average. No one else goes to the well more than once per 19 points.

Persistence aside, Sasha’s results are mixed: He wins about 45% of those points. That’s unimpressive compared to the ATP norm of 54%, and it’s particularly weak next to Alcaraz’s mark of 62%. Assuming that drop shots are, on average, hit from a neutral rally position, one in which each player has a 50% chance of winning the point, Bublik costs himself 3.3 points per thousand with his drop shot. In the last decade, only Benoit Paire has been worse.

On the other hand, the number rests on a big assumption. Alcaraz excels from the baseline; Bublik relies more on his serve. For any given situation–say, 5th stroke of a second-serve point, ball coming to the backhand side–Carlitos probably has a better chance of winning it, drop shot or not. Indeed, based on Match Charting Project data, Alcaraz wins 52% of points from that position. Bublik manages only 46%.

That’s typical. Here are the six situations in which Bublik hits the most drop shots, broken down by whether he is the server or returner, whether it’s a first- or second-serve point, the stage of the rally, and whether he’s faced with a forehand- or backhand-side shot. The table shows the probability that he wins the point if he doesn’t hit a drop shot:

Sv/Ret  Serve  Shot  Side  Exp W%  
Sv      1st    3rd   FH     57.4%  
Ret     2nd    4th   BH     42.8%  
Sv      2nd    3rd   FH     48.2%  
Sv      1st    3rd   BH     51.6%  
Ret     2nd    4th   FH     42.5%  
Sv      2nd    3rd   BH     46.1%  
Ret     1st    6th+  FH     42.2%

Only two of these scenarios favor Sasha: Plus-one forehands and plus-one backhands behind a first serve. Just about anything else and he’s the underdog.

Here are the same six situations, with expected point winning percentages for Alcaraz:

Sv/Ret  Serve  Shot  Side  Exp W%  
Sv      1st    3rd   FH     60.7%  
Ret     2nd    4th   BH     51.5%  
Sv      2nd    3rd   FH     57.3%  
Sv      1st    3rd   BH     54.1%  
Ret     2nd    4th   FH     53.6%  
Sv      2nd    3rd   BH     50.7%  
Ret     1st    6th+  FH     55.1% 

When Carlitos opts for a drop shot, he’s trading in what’s already a positive expectation for one that he hopes is even rosier.

Repeat this exercise for every situation in which Bublik has hit a drop shot, take a weighted average, and we find that had he not hit drop shots, he would have won 46.5% of those points. With that in mind, his 45.4% drop-shot winning percentage doesn’t look so bad.

The recalculation doesn’t tell us that Bublik’s drop shot is good, but it does make the tactic look more viable. We’re assuming that in the aggregate, all shot opportunities with the same profile (i.e. second-serve point, ball to the backhand for the fifth shot of the rally) are about the same. That’s just an approximation, so a gap of one percentage point could occur because Sasha chooses lower-percentage moments to hit the drop. There’s even a sliver of evidence that he does so: Eight of his charted drop shots are backhands on the seventh shot of the rally or later of his own first-serve points. Those sound like desperate efforts to finish a point he’s given up on, and sure enough, he lost all eight. Take those out of the equation, and his win percentage on drop shots is exactly the same as when he hits something else.

Drops in expectation

Go through the same exercise for every player, and the drop-shot leaderboard takes on a different look.

Some players, like Kei Nishikori and Nicolas Jarry, win a very high percentage of drop shot points and exceed expectations by a wide margin. Others, like Alcaraz, see less of a benefit from their drop shot, in part because their other options are so good. Still others, like Daniil Medvedev, win more than half of drop-shot points, but because of the rest of their game and the moments they choose to deploy the drop, they may be sacrificing some points when they do so.

Call the new stat Drop Shot Wins Over Expectation, or DSWOE: the ratio of drop-shot success rate to non-drop-shot winning percentage, taking into account the situations in which the player chooses the drop.

Among the 60 players with the most charted points since 2015, here’s the top of the list–the men who gain the most per drop shot–along with a few notable names in Bublik’s section of the list, plus the most extreme laggards:

Player                       Drop W%  Exp W%  DSWOE  
Nicolas Jarry                  65.3%   50.4%   1.30  
Lucas Pouille                  60.3%   48.1%   1.25  
Kei Nishikori                  68.1%   54.5%   1.25  
Sebastian Baez                 63.2%   50.9%   1.24  
Richard Gasquet                60.7%   50.0%   1.22  
Kevin Anderson                 53.8%   44.6%   1.21  
Reilly Opelka                  52.1%   43.5%   1.20  
Marton Fucsovics               58.2%   49.5%   1.18  
Alejandro Davidovich Fokina    59.3%   50.7%   1.17  
Roger Federer                  59.5%   51.4%   1.16  
Robin Haase                    54.7%   47.8%   1.14  
Frances Tiafoe                 54.6%   48.0%   1.14  
Pablo Carreno Busta            58.9%   52.2%   1.13  
Dominic Thiem                  57.1%   50.7%   1.13  
Carlos Alcaraz                 62.1%   55.7%   1.12  
Rafael Nadal                   61.5%   55.4%   1.11  
Andy Murray                    55.7%   50.5%   1.10  
…                                                    
Holger Rune                    51.4%   51.3%   1.00  
Grigor Dimitrov                47.7%   47.9%   0.99  
Alexander Bublik               45.4%   46.5%   0.98  
Daniil Medvedev                53.0%   54.8%   0.97  
Novak Djokovic                 50.8%   52.9%   0.96  
…                                                    
Stan Wawrinka                  45.3%   48.9%   0.93  
Milos Raonic                   38.0%   41.3%   0.92  
Benoit Paire                   42.9%   46.8%   0.92  
Tommy Paul                     47.0%   51.5%   0.91  
Aslan Karatsev                 39.0%   49.9%   0.70

Surrounded by names like Rune and Djokovic, Bublik doesn’t seem so bad. Alcaraz, on the other hand, doesn’t stand out as much. He and list-neighbor Rafael Nadal are outrageously good in rallies whether they hit a drop shot or not. Even a world-class drop shot is only so much better than a standard Rafa or Alcaraz topspin groundstroke.

Tour average is around 1.05, meaning that the typical player does a bit better when they hit a drop shot than they would have had they chosen a different shot in the same situation. That tells us something that we probably suspected: Players are generally good at choosing the right moment to unleash the drop.

With this more fine-grained notion of expectations, we can re-calculate the number of points per thousand that each player gains or loses from drop shots. It is a function of both success rate (relative to expectations) and frequency. Nishikori and Jarry get great results from the drop but employ it rarely; men like Alcaraz and Sebastian Baez gain more points overall because they hit droppers so much more often.

Here are the players who gain the most points, along with the five tour regulars at the bottom of the list:

Player                       Freq%  W% - Exp%  DPOE/1000  
Sebastian Baez                3.9%      12.3%        4.8  
Alejandro Davidovich Fokina   5.2%       8.5%        4.5  
Lucas Pouille                 2.9%      12.2%        3.5  
Carlos Alcaraz                5.4%       6.4%        3.4  
Richard Gasquet               2.8%      10.8%        3.0  
Robin Haase                   3.9%       6.9%        2.7  
Kei Nishikori                 2.0%      13.6%        2.7  
Frances Tiafoe                3.2%       6.6%        2.1  
Pablo Carreno Busta           2.8%       6.7%        1.9  
Nicolas Jarry                 1.2%      14.9%        1.8  
Fabio Fognini                 3.7%       4.7%        1.8  
Andy Murray                   3.3%       5.2%        1.7  
Dominic Thiem                 2.6%       6.4%        1.7  
Marton Fucsovics              1.9%       8.7%        1.7  
Roger Federer                 2.0%       8.1%        1.6  
…                                                         
Novak Djokovic                3.3%      -2.1%       -0.7  
Alexander Bublik              7.2%      -1.0%       -0.8  
Lorenzo Musetti               5.1%      -2.3%       -1.2  
Aslan Karatsev                1.2%     -10.9%       -1.3  
Benoit Paire                  5.4%      -3.9%       -2.1

Five (or 4.8) points per thousand might not sound like a lot, but it represents the difference between Baez having a place in the top 20 and residing well outside of it. Alcaraz still grades well here, if not as much as he did before making all of the adjustments. Bublik scores closer to neutral too. His drop shot is probably more useful for earning him highlight-reel screentime than it is for winning points, but it isn’t hurting him that much.

Side matters

Armed with these adjustments, we can compare each player’s forehand and backhand drop shots, as well. Bublik has a fairly wide split. He wins just over 50% of points when he hits a forehand drop shot, next to only 39% behind a backhand drop shot. His expectations when faced with a backhand are worse in general, but not that much worse. His forehand drop shot success rate is two percentage points better than if he went with a standard groundstroke, while his backhand drop shot is five points worse.

So Sasha, if you’re reading this: We all love your drop shots. But maybe take it easy with the backhands.

The best forehand drop shots, compared to how the player would have fared with a different shot, belong(ed) to Kevin Anderson, Sebastian Baez, Lucas Pouille, Marton Fucsovics, and Nishikori, with Roger Federer not far behind. The most effective backhand droppers are those of Jarry, Reilly Opelka, Pouille, John Isner, and Richard Gasquet. “Expectations” is the key word for Opelka and Isner: They didn’t win a lot of points once a rally was underway, so a moderately good drop scores very well by comparison.

Here is the field of 60 regulars from the last decade. As usual, top right is good, bottom left is… yikes, Aslan Karatsev.

There are innumerable way to divide these numbers even further, and I know you’re tempted. But with drop shots, there is only so much data. Some of the outliers here, like Jarry and Anderson, are probably a bit aided by luck. Men who don’t hit many drop shots might only have a few dozen attempts on their weaker side. The standouts probably are better than average, but limits of our data lead us to overstate their advantage.

At least with the forehand/backhand division, adjusted for how players would have fared with something other than a drop shot, we can get some hints as to how our faves can improve their games. Taylor Fritz has a strong backhand, and I doubt the points he’s losing with his backhand drop shot are making it any more effective. Alexander Zverev isn’t doing himself any favors with his occasional forehand droppers. Karatsev, well… not everyone can excel at everything.

Bublik, despite his negative numbers in the aggregate, has an effective forehand drop shot. With the power of his serve and forehand, he’ll continue to earn plenty of opportunities to use it. If he resists the urge to showboat on his backhand side, the court jester of the drop shot could continue to show off his touch and still earn a more coveted position in the tactic’s royal house.

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Also today: Wild cards and doping bans; Miami preview podcast

It is not easy to analyze the drop shot. Players don’t hit it very often, they sometimes hit it from very favorable or very unfavorable circumstances, and the goal of the shot sometimes extends beyond winning the point at hand. We can point to someone who hits droppers well and seems to win a lot of points doing so, but how much is the skill really worth?

Carlos Alcaraz is the poster boy for the modern drop shot. He loves to hit it–possibly too much–and when he executes, it’s one of the most stunning shots in tennis. At the business end of his Indian Wells campaign last week, he went to the well seven times against Alexander Zverev, ten times against Jannik Sinner, and three more in the final against Daniil Medvedev. He won 11 of those 20 points. That doesn’t sound so impressive, but Alcaraz could hardly complain about the end result.

To get a grip on drop shot numbers, we have a lot of work to do. What is a good winning percentage? Do any players suffer because they hit the drop shot too much? Is there a lingering effect from disrupting your opponent’s balance? Finally, once we have a better idea of all that, how does Alcaraz stack up?

Drop shot basics

To keep the data as clean as possible, let’s be specific about which strokes we’re looking at. While one can hit a drop shot in response to another drop shot (a “re-drop”), and it’s possible to hit a drop shot from the net in reply to a short volley or half-volley, those aren’t typically what we’re referring to. There are probably players (starting with Alcaraz!) who are better at that sort of thing than their peers, but those low-percentage recoveries aren’t today’s focus.

In this post, when I say “drop shot,” I mean a drop shot from the baseline, excluding all shots from the net, including responses to earlier drops.

The Match Charting Project gives us over 4,600 men’s matches to work with since 2015. Those 750,000 points include almost 35,000 drop shots. That works out to a drop shot in about 4.6% of points. Or from the perspective of a single player, it’s 2.3%, 1 out of every 44 points. The player who hits the drop shot ends the point immediately (via winner or forced error) about one-third of the time, and 19% of the droppers miss for unforced errors. Overall, the player who hits the drop shot wins the point 53.8% of the time.

From the 60 players with the most charted points to analyze, here are the 15 who win the highest percentage of points behind their drop shots:

Player                       Drop Point W%  
Kei Nishikori                        69.6%  
Richard Gasquet                      66.2%  
Nicolas Jarry                        65.3%  
Sebastian Baez                       63.2%  
Carlos Alcaraz                       62.1%  
Rafael Nadal                         61.3%  
Lucas Pouille                        60.3%  
Roger Federer                        59.7%  
Alejandro Davidovich Fokina          59.3%  
Roberto Bautista Agut                58.9%  
Marton Fucsovics                     58.2%  
Pablo Carreno Busta                  58.1%  
Jannik Sinner                        57.7%  
Dominic Thiem                        57.5%  
Andy Murray                          56.7%

Alcaraz does well here! Despite the presence of Kei Nishikori at the top, the list is heavily skewed toward clay-courters. Drop shots are a more central tactic on clay than on other surfaces, which works in both directions: Clay-courters are more likely to develop good drop shots, and players who have dangerous droppers are more likely to succeed on dirt.

Another skill that contributes to a spot on the list is good judgment. Nicolas Jarry doesn’t hit many drop shots, so he is probably picking the ripest opportunities when he does. There’s almost zero correlation between frequency of drop shots and drop shot success rate. Call it the Bublik Rule. From the same group of 60 tour regulars, here are the top 15 ranked by frequency:

Player                       Drop/Pt  Drop Point W%  
Alexander Bublik                7.2%          45.4%  
Benoit Paire                    5.4%          41.7%  
Carlos Alcaraz                  5.4%          62.1%  
Alejandro Davidovich Fokina     5.2%          59.3%  
Lorenzo Musetti                 5.1%          50.7%  
Holger Rune                     4.8%          50.9%  
Sebastian Baez                  3.9%          63.2%  
Robin Haase                     3.9%          55.1%  
Fabio Fognini                   3.7%          54.7%  
Matteo Berrettini               3.5%          52.0%  
Nick Kyrgios                    3.3%          54.9%  
Andy Murray                     3.3%          56.7%  
Novak Djokovic                  3.3%          50.4%  
Botic van de Zandschulp         3.2%          51.4%  
Frances Tiafoe                  3.2%          54.1%

Bublik may be turning things around: In the Montpellier final last month, he attempted 18 droppers and won the point 14 times. For a consistent high-frequency, high-success combination, though, we’re back to Alcaraz. Only Carlos, Alejandro Davidovich Fokina, Sebastian Baez, and Andy Murray (barely) appear on both lists.

Here are all 60 players in graph form. The top right corner shows players who hit a lot of drop shots and win most of those points. The closer to the bottom, the lower a player’s success rate; the closer to the left, the fewer droppers he attempts:

As a percentage of all points played, Bublik wins the most behind his drop shot. But it comes at a cost, since he hits so many of them, often sacrificing points because of it. If we assume that each drop shot is struck from a precisely neutral rally position, meaning that the would-be dropshotter has a 50% chance of winning the point, Bublik is losing points by going to the drop shot so often.

That’s a big assumption, and it probably isn’t exactly true for Bublik, or for anyone else. But if we stick with that for a moment, we can combine frequency and success rate into one number. Take the difference between success rate and 50% (that is, the gain or loss by opting for a drop shot), multiply that by frequency, and you get the percent of total points that the player wins by choosing the drop. The resulting numbers are small, so here’s the top ten (and bottom five) list showing points gained or lost per thousand:

Player                       Drop Pts/1000  
Carlos Alcaraz                         6.5  
Sebastian Baez                         5.2  
Alejandro Davidovich Fokina            4.9  
Richard Gasquet                        4.5  
Kei Nishikori                          3.8  
Lucas Pouille                          3.0  
Pablo Carreno Busta                    2.3  
Andy Murray                            2.2  
Roberto Bautista Agut                  2.2  
Rafael Nadal                           2.0  
…                                           
Jo Wilfried Tsonga                    -0.8  
Feliciano Lopez                       -1.3  
Aslan Karatsev                        -1.3  
Alexander Bublik                      -3.3  
Benoit Paire                          -4.5

Reduced to one number, Alcaraz is our dropshot champion. Six points per thousand doesn’t sound like a lot, but to invoke the familiar refrain, the margins in tennis are small. Beyond the top five or ten players in the world, one single point per thousand is worth one place on the official ranking list. Stars of Alcaraz’s caliber are separated by wider gaps, but it’s still a useful way to gain some intuition about the impact of these apparently miniscule differences.

The after-effect

In the hands of someone like Carlitos, the drop shot is a reliable way to win points. But the impact can go further than that. All sorts of tactics–drop shots, underarm serves, serve-and-volley–can theoretically be justified by some longer-term effect. If your opponent is camped out six feet behind the baseline and you want him somewhere else, a drop shot will surely give him something to think about.

This is hard to quantify, to put it mildly. How long does the effect of a drop shot last? Does it decay after each successive point? Does it disappear at the end of a game? On the next changeover? Ever? Jarry might need to hit the occasional drop shot to remind his opponent that he can do it, but Alcaraz doesn’t even need to do that. Everybody knows he’ll dropshot them, so he’s probably in his opponent’s head even before he hits the first drop shot of a match.

The evidence is unclear. About two-thirds of drop shots are hit by the server. I looked at the results of points immediately after a point with a drop shot, points two points later, and all the points that followed within the same game. When the server hits the drop shot, his win percentage on those subsequent points is worse than his win percentage on other points throughout the match–that is, non-dropshot points that didn’t follow so closely after he played a dropper:

Situation          Win%  
Next point        63.3%  
Two points later  62.6%  
Same game         62.5%  
All others        64.2%

I suspect that the dropshot effect (if there is one) is swamped by all the other influences at work here. Droppers typically occur in longer rallies, which might tire the server. The server might go for a drop shot when he runs out of ideas, another thing that might go through his mind as he prepares for the next point. This seems to work against Alcaraz more than other servers:

Situation          Win%  
Next point        62.0%  
Two points later  62.1%  
Same game         63.2%  
All others        65.0% 

The same pro-returner bias appears when we look at the results when it is the returner who goes for the drop shot. After seeing the numbers above, it’s tough to say that hitting a drop shot causes the higher success rate on subsequent points, but it is nonetheless a striking effect, especially for Carlitos:

Situation      Alcaraz W%     Tour W%  
Next point          44.0%       38.3%  
Two points later    41.8%       37.6%  
Same game           41.5%       37.9%  
All others          40.1%       35.8%

Whatever the mechanism here, it goes beyond “drop shot good, opponent confused.” More research is needed, and camera-tracking data would help.

Regardless of the after-effects (or lack thereof), the stats support the common contention that Alcaraz possesses a world-class drop shot. He might use it too often in some matches, and certainly there are individual situations in which he should have done something else. In the aggregate, though, the tactic is working for him. It produces more value than any other player’s dropper has done in the last decade. Tennis analytics is hard, but goggling at the game of Carlos Alcaraz is easy.

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Wild cards and doping suspensions

Simona Halep returned to action this week, thanks to a Miami wild card granted immediately after her doping suspension was reduced. Halep is well-liked, and there were few objections to her appearance in the draw. But Caroline Wozniacki, while careful to say she wasn’t specifically targeting Halep, said that she was against dopers getting post-suspension wild cards.

We’ve done this before. In 2017, Maria Sharapova returned from 15-month ban and immediately got a wild card to enter Stuttgart. The tennis world spent a few weeks in a dither about whether she’d get one to the French Open, too. She didn’t.

I wrote about the Sharapova situation at the time. I argued that Sharapova ought to get those opportunities. The reason I gave at the time was that it was better for the sport: She was one of the best players in the game, and fields would be more competitive with her than without her. Another reason is that without wild cards, it’s a long road back. Unranked after more than a year on the sidelines, a player needs to enter qualifying at ITFs, wait two weeks for those points to go on the official rankings (assuming they win!), and then use those rankings to enter (slightly) stronger events, with entry deadlines several weeks in advance of the tournaments themselves.

Climbing back up the ladder can take months. Is that part of the penalty? Is a 15-month suspension supposed to be 15 months of no competition, followed by 3-6 months of artificially weak, poorly remunerated competition? In team sports, this isn’t an issue, because coaches can put returning players in the lineup as soon as they’re ready.

As usual, the problem is that tennis doesn’t have unified governance. None of the various bodies in charge have an applicable policy. Sharapova was fine, and Halep will be fine, because stars get wild cards (if not as many as they would like), while lower-ranked players are stuck heading to Antalya to rack up ITF points. The discrepancy is particularly glaring in a case like that of Tara Moore, who missed 19 months but has been fully exonerated.

The WTA is apparently considering granting special rankings to players who have been cleared of doping charges or had their bans reduced, essentially treating them as if they are returning from injury. That’s better than nothing, but it wouldn’t address the more common scenario illustrated by Sharapova’s return.

I would go further and grant special rankings to any player returning from suspension. The term of the suspension is the penalty, period. Even better, and fairer to the field as a whole: Grant those special rankings in combination with a policy that restricts wild cards. For instance, Halep could have eight or ten entries into tournaments on the basis of her pre-suspension ranking, but no wild cards for her first year back. That way, individual tournament directors don’t need to re-litigate each doping ban, players have a predictable path to follow post-suspension, and superstars aren’t given any special advantages.

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Miami preview podcast

I had a fun conversation yesterday with Alex Gruskin, talking about my recent Iga Swiatek piece and previewing the men’s and women’s draws in Miami. Click here to listen.

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