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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Kei Nishikori’s Unbeatable Run in Deciding Sets

When Kei Nishikori defeated Roberto Bautista Agut in last week’s Barcelona quarterfinals, it was the seventh time in a row that he won a deciding set. By Nishikori’s standards, that’s nothing special. It is the fifth time in his career he’s put together a string of at least seven straight deciding-set wins, three of which he’s recorded since the beginning of last season.

The wider the perspective, the more impressive Kei’s deciding-set record. Since last year’s Australian Open, he’s won 27 of 30 matches that went the distance, including a 13-match winning streak from Halle to London. Back in 2011-12, he won 16 deciding sets in a row, including four against top-ten players.

In his career on tour, Nishikori has won 75 deciding-set matches and lost 20, for a winning percentage of 79%. Using any reasonable minimum number of matches, no other player has come close to that mark. You might recognize some of the other names on this list, ranked by record in deciding sets (minimum 80 matches):

Kei Nishikori   78.9%  
Bjorn Borg      74.7%  
Novak Djokovic  74.1%  
Jimmy Connors   69.8%  
Rafael Nadal    69.5%  
Andy Murray     69.4%  
Rod Laver       68.4%  
John McEnroe    68.1%  
Pete Sampras    68.0%

Kei’s career accomplishments don’t quite stack up with those of this crowd, but in terms of deciding-set performance, we’re looking at much more than an early-career fluke. While his numbers are a bit padded by matches that shouldn’t have gone the distance (like his early-round hiccups in Memphis this year against Ryan Harrison and Austin Krajicek), he has been almost as good when facing the best players in the game. Against top-ten opponents, he’s 17-6, good for a 74% winning percentage–a mark that would still put him near the top of the list.

Let’s return to Nishikori’s outrageous recent record of 27-3 in his last 30 deciding sets. Sure enough, no one has ever done better. Nine other players  have posted an equal mark in a span of 30 deciding-set matches, including Novak Djokovic, Rafael Nadal, Roger Federer, and Nishikori’s coach Michael Chang. Amazingly, Kei himself had already gone 27-3, back in 2011-12.

To break the tie among these accomplishments, we might look at the difficulty of the 30-match span, as measured by deciding sets against top-tenners. When Djokovic went 27-3, between 2011 Dubai and 2012 Canada, he played 15 of those matches against top-ten opponents,winning 14 of them. (Novak is also 27 of his last 30, including 15 of 17 against top-tenners.) When Nadal had his run, between 2008 Dubai and 2009 Paris, he faced 12 top-tenners, beating 10. Kei has faced only six, winning five.

It’s clear that Nishikori’s deciding-set prowess is a skill, not just a statistical fluke built on easy draws and luck. And based on the performance of the other players who have put together equally impressive deciding-set streaks, we can expect Kei to win most of his upcoming three- and five-setters.

Including streaks that overlap, there have been 27 instances in ATP history when a player won 27 of 30 deciding-set matches, excluding Kei’s and Novak’s current spans. In the ten deciding-set matches that followed each of those streaks, in each instance the player won at least five, and the average was just under seven.

Only once in ATP history has a player gone 27-3 in deciding-set matches and followed it up by winning nine of his next ten. If Nishikori is to match or better that mark, at least he’s assembled the right team: The player he’s chasing is Michael Chang.

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Novak Djokovic and the Best Fifty-Match Stretches

Few players have ever been as dominant as Novak Djokovic is right now. Over his last fifty matches, he has posted stats that are almost too good to be believed:

Armed with stats going back 25 years, we can see how Djokovic’s current performance compares with the best in recent ATP history. In some categories, he is indeed atop the list. In others, he’s merely very close to the best ever.

Let’s start with the simple matter of won-loss record. 47 wins in 50 matches is excellent by any standard. Only four players–Roger Federer, Rafael Nadal, Thomas Muster, and Djokovic himself–have done better. Pete Sampras also won 47 of 50 in a stretch in 1993-94.

The category in which Djokovic most clearly stands out is his performance against top-10 opponents. His 21 top-10 wins in a 50-match stretch outpaces the best of Nadal (18, in 2013), Federer (17, in 2006-07), and Andre Agassi (17, in 1994-95). Only 12 different players have won ten top-10 matchups in a 50-match stretch, let alone 20. Novak’s 23 top-10 matches is also the highest on record.

Then there are the bagels. In this span, Djokovic has won 13 sets by a 6-0 score. That’s not quite the best: Federer won 14 in his 2006-07 stretch. Sergi Bruguera (1993) and Agassi (1992-93) also show up here, with 13 bagels over the course of 50 matches.

Finally, let’s turn to aggregate statistics. Dominance Ratio (DR) is the ratio of return points won to serve points lost, and serves as a simple yardstick for–you guessed it–dominance. A DR of 1.0 indicates the two players were equal, 1.1 is a narrow win, and anything in the 1.5 range is a comfortable victory.

As Carl noted in that tweet, Djokovic has maintained a DR of nearly 1.5 over his last 50 matches. That’s not the best of all time–in fact, it’s not even Novak’s best. From 2013 Cincinnati to the second round of 2014 Monte Carlo, Djokovic posted a cumulative DR of 1.49, just edging out his current streak.

But neither mark is number one on the list. As with so many other categories, this one belongs to 2006 Federer. From the 2006 Halle final through the end of the 2007 Australian Open, Fed won 49 of 50 matches, 16 of 16 matches against the top 10, served 14 bagels, and posted an overall DR of 1.54. It would take an extremely strong performance from Djokovic over the next few weeks–even by his own standards–to reach those heights.

If you prefer the more traditional metric of total points won, Fed is still your number one, at 56.84% over that 2006-07 span. A different streak of Novak’s–his historic 2011 run–comes in a very, very close second, at 56.77%. Nadal put together a stretch in 2012-13 of 56.6%. The entire top ten is dominated by these three guys; the only other player who has won more than 56% of total points over 50 matches is Guillermo Coria, who did so in 2003.

Comparing Novak’s current streak to the rest of the field merely emphasizes how much distance he has placed between himself and the pack. Federer’s DR over his last 50 matches is a very respectable 1.37, with Nadal not far behind at 1.29. Kei Nishikori and Milos Raonic aren’t far behind in the official rankings, but by this measure they have an immense amount of ground to make up, with cumulative DRs of 1.17 and 1.16, respectively.

For Djokovic right now, a number that starts with 1.1 is a bad day. In his last 50 matches, he has sunk below 1.2 only seven times. Whichever metric you prefer, we’re watching one of the great performances of modern tennis history.

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Roger Federer’s Impressive but Not-Entirely-Relevant Dominance of the Istanbul Field

Roger Federer has faced 14 of the 27 other players in this week’s Istanbul field, and owns a career record of 59-1 against them. His one loss came to Jurgen Melzer, while more than half of his win total is thanks to his decade-long dominance of Mikhail Youzhny (16-0) and Jarkko Nieminen (14-0).

It’s rare that players of Federer’s stature contest such small events, so we don’t expect to see such lopsided head-to-heads very often. In fact, if we limit our view to events where a player faced at least 10 of the other entrants, it is only the 17th time since 1980 that someone has entered an event with a won-loss percentage of 95% or better against the field.

Federer himself represents two of the previous 16 times this has happened. The most notable of them is 2008 Estoril. He had previously faced 14 of the other players in the draw, and had never lost to any of them in 46 meetings. There are only four other instances of players undefeated against a field, all between 1980 and 1984 and in many fewer matches.

The most eye-grabbing of those early-80s accomplishments was Ivan Lendl‘s record entering the 1980 Taipei event. He had faced 15 of the men in the draw, posting a record of 24-0 up to that point. Lendl’s name is the most common on the list, having entered tournaments with a 95% won-loss record against the field on four different occasions, highlighted by a 79-4 mark against the other competitors at Stratton Mountain in 1988.

Federer won the 2008 title in Estoril and Lendl claimed the 1980 trophy in Taipei, but Lendl was ousted in the second round of the 1988 Stratton Mountain event. Federer has also demonstrated that a stratospheric record against the field is no guarantee of success.

After Estoril, Roger’s second-best record entering an event was in Gstaad in 2013. He held a 73-3 record against the field, with each of the three losses coming against different opponents. He lost his opening-round match in straight sets to Daniel Brands. His record against the field of the previous week’s Hamburg event was nearly perfect as well at 137-8, but Federico Delbonis stopped him in the semifinals there.

Rafael Nadal can tell a similar story. His best record against a field was in Santiago two years ago, coming back from injury. He had lost only 1 of 28 career matches against the other players in the draw. That week, Horacio Zeballos doubled Rafa’s loss count.

In fact, of the 16 times that a player went into an event with a 95% or better record against the field, the favorite won only six of them. Expanding the sample to records of 90% or better, the dominant player won 30 of 72 titles. Neither mark is as good as we’d expect if the historically great players continued to win matches at a 95% or 90% clip. In practice, head-to-head records just aren’t as predictive as they seem to be.

As is evident from some of the examples I’ve given, there are mitigating circumstances for many of these losses, and they aren’t entirely random. These days, when a player enters an event that seems below him, there’s a reason for it. Nadal rarely plays 250s; he was doing so to work his way back into match form. Federer rarely seeks out smaller events on clay; he was experimenting with a new racket.

This week, there’s no reason why Fed shouldn’t perform at his usual level–at least his usual level for clay–and win the four matches he needs to claim yet another title. But if he suffers his second loss against the players gathered in Istanbul this week, it won’t be quite as much of a shock as that 59-1 record implies.

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Match Charting Project: More Matches, More Data, New Spreadsheet

The Match Charting Project keeps growing, and starting today, even more of the data is available for anyone who wants it. Several new contributors have helped us pass the 750-match milestone, having added an average of two matches per day since I first published the raw data.

New spreadsheet

The Match Charting spreadsheet now does a lot more. As you chart each point, the document updates stats for the match–both total and set-by-set. You’ll find the same stats you see on television (aces, double faults, winners, unforced errors, etc) along with some that are a little less common, like winning percentage in different lengths of rallies, and most consecutive points won.

In other words, As you chart the match, you’ll have access to many of the same stats that commentators do. Here’s what it looks like:

danka

If you’ve hesitated to try charting because you couldn’t see what was in it for you, I hope this changes the calculation a bit.

Click here to download MatchChart 0.1.4.

(If you prefer to use the lighter-weight version 0.1.2, that’s fine too.)

New data

About a month ago, I published the point-by-point data from all charted matches.  In raw form, it’s a bit daunting, and it’s more than what’s necessary for many interesting research projects.

Today, I added 15 different aggregate stats files for men, and another 15 for women. These contain the data that is shown in each charted match report. For instance, if you find it interesting that Simona Halep hit 14% of her backhands down the line in the Indian Wells final, you can take a look in the ShotDirection stats file and compare that number with the results from Halep’s other charted matches, or all matches in the database as a whole.

You can find these files (along with the updated raw data for 760+ matches) by clicking here.

Chart some matches

If you haven’t already, now is a great time to start charting professional matches and contributing to the project. An enormous number of matches are televised and streamed, and as the database of charted matches grows, there’s more and more useful context to all the data we’re generating.

You can start by jumping into the ‘Instructions’ tab of the new MatchChart spreadsheet, or for other tips, you can start with my blog post introducing the project.

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Free ATP and WTA Results and Stats Databases

The vast majority of my men’s and women’s tennis results and stats databases are now free for anyone who wants to use them.

ATP Results and Stats:

  • Tour-level results back to 1968, with tons of data on both players in each match (age, handedness, country, rank), and matchstats from 1991-present.
  • Almost a decade of tour-level qualifying matches, with matchstats for the last few years.
  • Challenger results back to 1991, with matchstats for almost the last ten years.
  • Futures (and Satellite) results back to 1991.
  • Linked biographical and rankings data (introduced here).

WTA Results:

  • Tour-level results back to 1968, with the same player data as in the ATP files.
  • Tour-level qualifying matches.
  • Over 220,000 ITF main-draw matches.

Click the links to access the files. Enjoy!

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Free ATP and WTA Ranking Databases

More data!

Today I’ve made available my entire ATP and WTA ranking databases through the end of the 2014 season. In addition, you’ll find my complete player tables, which include birthdate, country, and handedness for every player who has ever been ranked or played a tour-level match. (Plus thousands more players, who are included in the database for other reasons.)

This is all the data you need to research all sorts of topics, like the rise and fall of certain countries in the rankings and the changing age of top 10s, 50s, and 100s.

This is the third major dataset I’ve published this week, and more is on the way.

ATP rankings are here, and WTA rankings are here. Enjoy!

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