Category Archives: Withdrawals and Retirements

Facts, Figures and Myths About Walkovers

Novak Djokovic advanced to the final of the Miami Masters today when Kei Nishikori withdrew from the event due to injury. Oddly, it was the second match at the Sony Open that Djokovic didn’t have to play, as Florian Mayer pulled out before their scheduled third round match.

It’s a rare occurrence in professional tennis–so rare that it had only happened once since 1968, when several players benefited from multiple walkovers at the French Open. In Miami two years ago, Andy Murray also skipped his third round and semifinal matches, as both Milos Raonic and Rafael Nadal dropped out due to injury.

The fact that it was Djokovic who got the free pass immediately gave rise to all sorts of speculation. Will the lack of match play hurt the Serbian? Does Novak get more walkovers than most? Are opponents more likely to withdraw if they’re facing a top player?

Let’s take these questions in order. I addressed a similar issue a couple of years ago in this post. Walkovers are rare, but the available evidence suggests that there’s no positive or negative effect from winning via withdrawal. A player’s chances of winning his next match are roughly what they would’ve been anyway.

Djokovic does gain from walkovers more often than the average player, but he’s far from the top of the list. Opponents have withdrawn five times in his 695 matches, good for 0.7%, roughly the same rate as opponents of Murray, Nadal, Roger Federer … and Donald Young and Dmitry Tursunov. Jo Wilfried Tsonga has benefited from six walkovers in 432 matches, a 1.3% rate, highest among tour veterans.

Top players win by walkover more often than others–but as we’ll see in a moment, it isn’t because they are top players. It’s intuitive to figure that mildly injured players are more likely to take the court if they think they have a better chance of winning, but the evidence suggests there’s little, if any, effect.

Men ranked in the top five win by walkover 0.6% of the time, while those in the next five get free passes 0.3% of the time, and most of the rest of the pack benefits at the tour average rate of 0.2%–once every 500 matches. (All of these aggregate rates are based on tour-level matches from 1991 through 2014 Indian Wells.)

For the most part, top players get walkovers because they hang around until the late rounds of tournaments. Walkovers occur at the highest rate in the quarterfinals of events, when 1.1% of matches end before they begin. Round-of-16 contests are almost as bad, at 1.0%, and semifinals are also considerably more walkover-prone than average, at 0.6%.

When we take these dangerous middle rounds out of the equation, the number of walkovers shrinks, as does the difference between top players and the rest of the pack. Less than 0.15% of pre-R16 matches end in walkover, and the rate at which top-five players benefit from them falls to 0.4%. That’s still more frequent than the rate for the rest of the field, but keep in mind the tiny numbers we’re dealing with here. It’s 13 walkovers in over 3000 matches. Take away five of those withdrawals–roughly two per decade–and the top five would benefit at the same rate as players ranked 16-20.

It’s not as interesting a narrative, but it appears that players usually withdraw when they are too injured to compete, and that’s most likely to happen midway through a tournament. The highest-ranked players benefit–because of their previous success on the court, not their intimidating influence off of it.

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Trends and Perspective on WTA Retirements and Withdrawals

Yesterday, there was no women’s singles at Indian Wells. Both Victoria Azarenka and Sam Stosur pulled out of their quarterfinal matches, presenting a very obvious target for anyone concerned about an injury bug in women’s tennis.

Last year, WTA retirements hit an all-time high of 4.8% of tour-level matches, almost a full percentage point above the 3.9% of matches that were not completed in 2006.  While part of the injury total was due to stomach bugs in China and food poisoning at Indian Wells, the overall trend has been upward for about 30 years:

WTArets

While it’s less clear that players are any more likely to pull out of Grand Slam matches (the dark red line in the graph above), there’s no doubt that more WTA matches are ending due to injury than they did 10, 20, or 30 years ago.

In a moment, I’ll explain why this is happening, and why the trend is unlikely to reverse itself anytime soon.  But first, some perspective on yesterday’s programming disaster.

Since there was nothing else to talk about yesterday in the world of women’s tennis, it was inevitable that the subject of injuries dominated. (Thanks to Federer vs. Nadal on the card, it wasn’t nearly as bad as it could have been.) Taking a tournament-wide view, though, this year’s Indian Wells WTA event has been a positive on the health front.

Women’s tennis has seen more than 1 in 50 tour-level matches end with W/O or RET in the score for more than 15 years.  Yesterday’s two withdrawals were the first two incomplete matches of the entire event–including qualifying!  Assuming we get through the semifinals and final without any further problems, that’s 93 of 95 (97.9%) of main draw matches complete, and 129 of 131 (98.5%) of main draw and qualifying matches complete.  Last year, while food poisoning dominated the headlines, there were at least three injury-related retirements from the singles draw, and two years ago, there were five.

These two quarterfinal withdrawals were bad news for television and fans, but they don’t represent a trend.

High stakes, high risk

While Indian Wells has been mostly injury-free, it also shouldn’t be seen as a trend in the positive direction.  WTA players (and ATPers, for the same reasons) are going to keep showing up at tournaments less than 100%, developing health problems midway through tournaments, and generally not finishing all the matches they start.

This isn’t because of too many hard courts, slower balls, mandatory events, doping, or even runaway racquet technology.  It’s because the financial stakes in tennis–and with it, severe inequality in the ranks–are climbing even faster than the injury rate.  The level of fitness required to compete at the highest level is always increasing, and players are forced to choose between trying to keep up or probably falling away.

A simpler example of this phenomenon, and one that makes it easier to illustrate the point, is in competitive distance running.  Marathoners rarely run more than two marathons per year, and there is very little room at the top.  Run a marathon in 2:04 and you’re a superstar. 2:05 or 2:06 and the sponsors will keep supporting you.  If you can’t break 2:10, you’re probably working full-time at a local shoe store.

The most straightforward way to improve your marathon time is to train harder, whether that means more mileage over a several-month training period or more aggressive workouts.  When the choice is between 2:05 and oblivion, the incentives are heavily structured toward overly aggressive training.  There’s not much difference between finishing with a 2:10 compared to overtraining, getting injured, and not finishing at all.

Tennis, of course, is a bit more forgiving.  You don’t need to be one of the top 10 in the world to make a decent living, but then again, to remain in the top 10, you must consistently beat players on the fringes of the top 100, where the incentives are not that different from those in distance running.

As the stakes increase, players are more willing to skirt the edge between hard training and over training.  And while players are getting closer to that line, they are hardly going too far–at least according to their own incentives.  Sure, we’d like to have seen Vika play yesterday, but a few retirements over the course of the year isn’t going to stop her from regaining the #1 ranking.  Two years ago, she pulled out of her quarterfinal with Caroline Wozniacki after only three games–and then started a twelve-match winning streak the following week.

If there were more matches on clay, players would simply push themselves harder on clay courts.  (Anyway, there is almost exactly the same percentage of WTA retirements on clay as there are on hard.)  Same thing if the balls played faster.  If there were fewer mandatory events, we’d see top players engaging in longer periods of hard training. Probably more exhibitions, too.

There are no incentives–nor should there be–for players to stay healthy for the duration of 100% of their matches.  If we want the best players in the world to entertain us with the best possible tennis they can play, retirements and withdrawals are something we’ll have to learn to accept.  We won’t get one without the other.

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Janko Tipsarevic and the Masters of Retirement

When Janko Tipsarevic retired six points away from defeat against Jerzy Janowicz on Friday, many tennis fans were … unsurprised.   The Serb has quite the record when it comes to quitting early, having retired from matches at all four Grand Slams, the Olympics, and nearly half of the Masters 1000 events.  He has retired on every surface and in every round.

It’s hardly a record to be proud of.  Tipsarevic’s departure on Friday was his 17th career tour-level retirement–about 1 in every 25 matches over his 434-match career.  His “retirement rate” of 3.9% is the highest among active players with at least 400 matches.  It’s more than double the tour average of about 1.5%.

But that “at least 400″ hides some context.  Expand the field to a still-respectable minimum of 200 tour-level matches and we have the following leaders in career retirement rate:

Player              Matches  Ret Rate  
Sergiy Stakhovsky       209      4.8%  
Michael Llodra          370      4.6%  
Yen Hsun Lu             222      4.5%  
Janko Tipsarevic        434      3.9%  
Denis Istomin           211      3.8%  
Paul Henri Mathieu      456      3.7%  
Filippo Volandri        367      3.5%  
Potito Starace          347      3.5%  
Xavier Malisse          531      3.0%  
Viktor Troicki          300      3.0%

Tipsy is still a standout, yet not an egregious one.  Both Paul Henri Mathieu and Xavier Malisse have retired in three of the four slams.  Michael Llodra has dropped out of Wimbledon three times, and the US Open twice.  (Not to mention retiring against Jo Wilfried Tsonga three times, and perhaps more remarkably, against both Tipsarevic and Mathieu.)

For a fuller view of the state of ATP retirement–including the 22 members of the top 100 who have never done so–click here for a sortable table with more fun stats.  (A few numbers are different than above, because my full database doesn’t yet include 2012 Bercy.)  Janko may quit early, but that doesn’t mean you have to.

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Withdrawal Effects

Yesterday, Mardy Fish withdrew from his fourth-round match against Roger Federer.  As we saw earlier today, Federer may gain some benefit from the extra rest, but with the additional rest days built into the grand slam schedule, Roger runs the risk of getting too little time on court.

What’s the true effect, then?  Will the extra rest make Federer an even bigger favorite in his quarterfinal match against Tomas Berdych?  Or will match-court rust hold him back?

As it turns out, there is virtually no effect.  Players handed a walkover win almost exactly half of their next matches, and a closer look at those matches reveals that 50% is about what we would’ve expected from them, walkover or not.

To hunt for a potential relationship, I found 139 ATP main draw walkovers since 2001 where the winner went on to play another match at the same tournament–in other words, excluding finals.  While it may seem that players tend to withdraw when they’re least likely to win a match (as with Fish this week, or like the other two players to withdraw before facing Federer this year), there’s nothing to that theory, either. The average pre-match odds of the withdrawing player are about 51%.

Thus, we can work on the assumption that there’s little bias in the pool of 139 men who received a free pass to the next round.  For every Federer, there’s a Donald Young advancing uncontested over Richard Gasquet.  Balancing the withdrawals of players without a chance may be higher-ranked players who are quicker to withdraw because their success allows them to play it safe and make longer-term decisions.

In the 139 follow-up matches, our players went 67-72, winning 48.2% of the time.  Prematch predictions (generated by Jrank) would have projected a winning percentage of 48.9%.

If we narrow the search to slams, we get a nearly-meaningless pool of only 12 matches.  The player coming off the walkover went 6-6; prematch numbers would’ve predicted 7-5.  Perhaps rust does play a small part; considerably more likely is that the walkover simply doesn’t affect the beneficiary.

For Federer fans, though, there’s little reason for concern.  This is the ninth time in his career he’s advanced via walkover, and he’s only lost the next match twice.  One of those was in 2002.  The other was in Indian Wells in 2008.  The man who beat Fed?  Mardy Fish.

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