Category Archives: Return stats

Nick Kyrgios and the Minimum Viable Return Game

No matter how well a player serves, he still needs to win some return points. While one-dimensional ATPers such as Ivo Karlovic and John Isner have demonstrated that an unbreakable serve alone can get you a steady paycheck and some quality time in the top 20, their playing style has never translated into a prolonged stay in the top ten.

Nick Kyrgios isn’t quite as tall as Isner or Karlovic, but his numbers are similar. In the last year, he has won 31.7% of return points, third-worst among the top 50, ahead of only those two players. In fact, since 1991, only five players have lasted a full season at tour-level while winning a lower percentage of return points. To make an impact in the upper echelon of the men’s game, the Australian will need to improve his return game in a big way.

To win matches, you need to break serve or win tiebreaks, and most players don’t demonstrate any particular tiebreak skill. That leaves breaks of serve, and to break serve, you need to win return points. Almost all ATP tour regulars win between 29% and 43% of return points, so a single percentage point or two is a meaningful distinction. While Milos Raonic‘s rate of return points won over the last 52 weeks is a Kyrgios-comparable 32.1%, no other top-ten player is below 36%.

If Kyrgios is to crack the top ten without any substantial improvement in his return game, Raonic is the model. Last year, Milos finished the season at #8 in the rankings despite having won only 33.7% of return points. That’s the lowest rate on record for a player with a year-end ranking in the top ten, and only the seventh time since 1991 that a RPW% below 35% earned someone a spot in the top ten.

Even at 33.7%–two percentage points higher than Kyrgios’s current rate–it took a remarkable run of tiebreak success for Raonic to win as many matches as he did. Milos won 75% of tiebreaks last year, a rate that almost no one has ever sustained beyond a single season. In other words, if Raonic is to continue winning matches at the same pace, he’ll probably need to post better return-game results.

To earn a place in the elite of the top five, the return-game threshold is even higher. Only two players–Pete Sampras and Goran Ivanisevic–have finished a season in the top five with a RPW% below 36%, and only two more–Andy Roddick and Stanislas Wawrinka–have done so with a sub-37% RPW%. Roger Federer, the most serve-oriented of the big four, hasn’t posted a RPW% below 38% in fifteen years.

The difference between 32% and 36% is enormous. To use a baseball analogy, a similar gap in batting average would be, roughly, from .240 to .280. The effects are equally meaningful. At 32%, a player is breaking serve roughly once per eight return games–considerably less than once per set. At 36%, he’s breaking serve almost once per five return games. Improve a few more percentage points to 39%, and he’s breaking every fourth game, almost twice as often as Kyrgios is now.

Those break rates are simply a way of quantifying what we already know at a general level: Players with strong return games have the power to decide matches. The more one-dimensional the playing style, the more likely a match is decided by just a few key points. And the smaller that number of points, the more that luck plays a part.

Of course, luck cuts both ways. It’s what makes players like Isner and Kyrgios so dangerous. Someone like Novak Djokovic or Rafael Nadal can usually dictate play, but against an unbreakable opponent, it all comes down to a few points in a couple of tiebreaks. So big servers tend to rocket into the top 30 or 40. A fifty-fifty winning percentage, especially coupled with a big upset and an occasional deep run at a big tournament, is plenty good enough to earn a spot that high in the rankings.

But without at least a mediocre return game, it’s tough for a big server to get beyond that level. Isner has managed it by winning tiebreaks at one of the best rates of all time, and even he has barely dipped his toe in the top ten. Raonic is a substantially better returner than the American, and it remains to be seen whether he can sustain his impressive tiebreak winning percentage and keep a spot among the game’s best.

Fortunately, Kyrgios has plenty of time to improve and break out of the mold of a one-dimensional big server. If he hopes to make a mark beyond the occasional upset and a home at the fringes of the top 20, that’s exactly what he’ll need to do.

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The Unaceables

Last night, Florian Mayer solved the John Isner serve, breaking the American three times en route to a straight-set victory.  Mayer is known as a tricky opponent, but not as a particularly good returner.  He had never played Isner before, though he beat Ivo Karlovic in Miami last year.

One element of his success is that he got his racquet on the Isner serve.  Over the last 52 weeks, Isner has amassed a 17.1% ace rate, meaning that about one in six of his serves are untouchable.  Last night, he barely managed 10%, as Mayer allowed him only six aces.

We might wonder: Is this is a skill of Mayer’s that we’ve failed to notice before?  At first glance, it doesn’t appear to be.  While Mayer often holds his opponents to low ace numbers, he’s had some horrible performances in that department, allowing Feliciano Lopez a 20.4% ace rate in Shanghai last year, Thomaz Bellucci 15.5% in Madrid on clay, and while playing injured, he ignominiously allowed Ivo Karlovic a 50% ace rate at last year’s Cincinnati Masters.

We can answer this question not just for Mayer, but for every regular on the ATP tour.  While some servers hit far more aces than others, ace rate is influenced by both the server and the returner.  Mayer himself is a good example.  In the last 52 weeks, he’s had eight matches in which at least one in ten serves went for an ace.  But in five other matches, he didn’t hit a single one!  Some of the variation is due to good and bad serving performances, but a substantial part can be explained by the man on the other side of the net.

As  it turns out, last night was an aberration for the German.  Mayer is below-average at ace prevention, allowing 8% more aces than an average player, ranking 80th among the 139 active players whose results I analyzed.

I looked at every 2011 and 2012 match, using only those matches in which both players racked up 10 matches in the last fifteen months.  After calculating each player’s ace rate, I generated an “expected” number of aces for each returner.  Simply tallying how many aces a player allowed isn’t good enough–this way, we adjust for the quality of the server.

Mayer, for instance, played 70 matches in that span against opponents who also played at least 10 matches.  (I excluded guys who played fewer than 10 because their ace rate in such a small number of matches may say more about their opponents than themselves.)  In his 4812 return points, he allowed 345 aces.  But based on the serving abilities of his opponents, he should have allowed only 321.  Those numbers will look a little better after last night, but not enough to move him up very much in the rankings.

By contrast, the best returners get their racquets on just about everything.  Atop the list is Gael Monfils, who allows barely half the aces that we would expect him to.  The top eight returners all reduce expected ace rates by at least a third.

In the table below, I’ve shown these stats for the ten players who appear to be the best at avoiding aces, along with 20 other players of interest.

Player                 Rank  Matches  vAce%  expAce%    Diff  
Gael Monfils              1       62   3.5%     6.8%    -48%  
Benoit Paire              2       23   3.8%     6.3%    -40%  
Andy Murray               3       81   4.4%     7.3%    -39%  
Stanislas Wawrinka        4       61   4.2%     7.0%    -39%  
Cedrik Marcel Stebe       5       12   3.2%     5.2%    -38%  
Viktor Troicki            6       70   4.3%     7.0%    -38%  
Gilles Simon              7       77   4.7%     7.3%    -36%  
David Ferrer              8       90   5.1%     7.8%    -35%  
Carlos Berlocq            9       53   4.7%     7.0%    -32%  
Mardy Fish               10       71   5.7%     8.3%    -31%  

Jo Wilfried Tsonga       14       89   5.7%     7.9%    -28%  
Roger Federer            20       92   6.0%     7.9%    -24%  
Novak Djokovic           22       89   6.4%     8.4%    -24%  
Kei Nishikori            32       63   5.8%     7.0%    -17%  
Rafael Nadal             34       91   7.4%     8.8%    -16%  
Nikolay Davydenko        38       60   5.8%     6.7%    -14%  
Sam Querrey              39       35   6.7%     7.8%    -14%  
Milos Raonic             40       60   6.7%     7.6%    -12%  
Kevin Anderson           53       74   7.5%     8.0%     -6%  
John Isner               59       68   7.6%     7.8%     -2%  

Radek Stepanek           73       62   8.6%     8.0%      6%  
Lukasz Kubot             74       44   8.5%     8.0%      7%  
Ivo Karlovic             78       45   7.9%     7.3%      7%  
Juan Martin Del Potro    81       84   8.8%     8.1%      9%  
Tomas Berdych            91       87   8.5%     7.6%     12%  
David Nalbandian        102       43   9.4%     7.9%     20%  
Arnaud Clement          120       17   9.3%     7.2%     29%  
Andy Roddick            130       55  11.8%     8.3%     42%  
Bernard Tomic           135       38  12.8%     8.5%     50%  
Olivier Rochus          139       36  14.7%     7.2%    103%

Before we go anointing Monfils and Benoit Paire the greatest returners in the game, it’s important to remember the serious limitations of the ace stat.  Much more important is getting the return in play.  But except for Grand Slam matches, we don’t have those numbers. In the meantime, we can use ace rate and return points won as proxies for return skills.

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