Who Actually Excels in Tiebreaks?

Italian translation at settesei.it

I’ve never understood the fixation that some fans and commentators seem to have with tiebreak winning percentage.  Sure, winning tiebreaks is nice, but it seems obvious that the main cause of exemplary tiebreak performance is being good at tennis.  Though some players may in fact be better than others at this facet of the game, a big part of what tiebreak winning percentage tells us is about general tennis skill.

In other words, Roger Federer is very good at tiebreaks because he is very good at serving and returning, the same skills that get him so many wins, regardless of whether any of the sets go to tiebreaks.

If we ignore tiebreak winning percentage, what are we left with?  It’s still tempting to wonder whether some players have a kind of special skill–calm under pressure, a particularly consistent serve–that leads them to outperform expectations in breakers.

The key word there is “expectations.”  Given Federer’s general ability on the tennis court, we should expect him to win most tiebreaks–for example, two of the last three breakers he’s played came against Stanislas Wawrinka, who he should beat regardless of the format.  But our intuition will fail us if we look at Federer’s match record and try to estimate how many tiebreaks he should have won, then compare the “should” to the “did.”

Expected tiebreaks

Sounds like something computers do better than humans.  Given a player’s percentage of service and return points won in a certain match, we can estimate how likely he was to win a tiebreak–on the assumption that his performance level stayed the same throughout the match.

If two players are equally matched, each one would be “expected” to win 0.5 tiebreaks.  That’s nonsensical for a single match, but over the course of this season, we see that of John Isner‘s 53 tiebreaks, the algorithm would expect him to win 29.  In fact, he has won 38, exceeding expectations (in raw terms, anyway) more than anyone else on tour this year.

This gives us two stats that offer more insight into a player’s tiebreak performance than “tiebreaks won” and “tiebreak winning percentage.”  The raw number, the difference between actual tiebreaks won and expected tiebreaks won, tells us how many additional sets a player has taken because of his tiebreak performance.  Call it TBOE: TieBreaks Over Expectations.  A similar rate stat is derived by dividing TBOE by the number of tiebreaks, allowing us to compare players regardless of how many tiebreaks they played.  Call that one TBOR: TieBreak Outperformance Rate.

As we’ve seen, Isner is the 2012 king of TBOE, performing well in tiebreaks and playing far more of them than anyone else on tour.  Yet three players–Steve Darcis, Andy Murray, and Jurgen Melzer–have done better by TBOR, exceeding expectations at a greater rate than Isner has.  Darcis is particularly remarkable, winning 16 of his 19 tiebreaks through last week, despite his serve and return rates in those matches suggesting he should have won only 10 of them.

(And in Vienna on Monday, he won another one, extending his already untouchable lead over the pack.)

I’ll have more to say about this tomorrow, including a look at just how much meaning we can extract from TBOE and TBOR.  In the meantime,  look after the jump for the current 2012 leaderboard–through Shanghai, sorted by TBOR, minimum 15 tiebreaks.

Continue reading Who Actually Excels in Tiebreaks?

What Matters in Tiebreaks?

Italian translation at settesei.it

Players and fans tend to look at tiebreaks as a unique part of the sport of tennis, perhaps one susceptible to special skills.  The ATP website last week devoted an article to what those skills might be.  Players generally seemed to agree that it was nice to have a good serve, and a good return would also be handy.  Clearly, more analysis is needed.

Let me give you my hypothesis.  Tiebreaks are pressure packed, and pressure can affect any part of a player’s game.  But in general, they should impact some parts more than others.  You could make the case for either side of the ball–on the one hand, serving is a more “automatic” activity; on the other, there’s more time to think before each serve, and thinking can be dangerous when the pressure is on.  This is where it’s nice to have some data.

I found 388 tiebreaks from the last eight ATP slams.  For each one, I compared each player’s winning percentage on serve during the first 12 games of the set to his winning percentage on serve during the tiebreak.  If players were robots, there might be a difference between the set and the tiebreak for any given match, but in general, the numbers should be the same.

But players aren’t robots.  As it turns out, players win more return points than expected during tiebreaks.  The difference is noticeable if not enormous: about one more return point than expected every three matches.

Thus, tiebreaks are different from the sets that precede them in one of two ways.  Either some players are unable to serve up to their usual standard during tiebreaks, or some players manage to raise their return game in tiebreaks.

A breakdown by tournament suggests the answer.  The difference between server winning percentage in sets and tiebreaks is about the same for the Australian Open, the US Open, and Wimbledon, but is less than half as much at the French.  It seems, then, that faster courts give returners a bigger boost in the breaker.  A more likely interpretation is that servers are unable to hold on to their advantage on faster courts.  There’s less of an advantage to lose on clay.

My hypothesis at the outset focused on pressure, and combined with the numbers, it suggests that players are more affected by pressure when serving than when returning.  It’s also possible that players find it more difficult to get into a serving rhythm with only two serve points at a time.  It’s also possible that returners are less likely to concede aces during tiebreaks, meaning that the same serve quality and return potential results in more return points won.

Whether it is a matter of server timidity or returner aggression, there are certainly fewer aces in tiebreaks.  In these 388 tiebreaks, there were 83 fewer aces than would be expected if players kept acing at the rate of their first twelve games.  Given the relative infrequency of aces, that’s a more striking decrease than that of service winning percentage in general.

This analysis is hardly the final word.  But for aspiring tiebreak masters, it does offer a slightly more specific prescription than “get better at tennis.”  Rather than assuming that the tiebreak is all about the serve, recognize that returners have a slight advantage.  On serve, players can improve simply by ignoring the pressure (easy, right?) and serving as well as they did during the set.  When returning, players can be more aggressive in the knowledge that in general, servers will not be.

After all, a good serve may be the key to tiebreak success, but only if the serve is as good as usual in the breaker.

The Case for the Race

Last week, Peter Bodo argued in favor of giving the ATP year-to-date “Race to London” more weight over the traditional rolling 52-week ranking.  It’s a relevant point right now, when Roger Federer leads in the 52-week tally, but Novak Djokovic dominates in the year-to-date numbers.

In other words, Fed is racking up more records at #1 while Djokovic will almost certainly go in the books as the top player of 2012.  Bodo doesn’t go far enough: The old-fashioned rankings are weird, confusing, and–why stop there?–bad for tennis.

In most of the world’s most popular sports, everybody starts the year with a clean slate.  Imagine if a baseball team opened their schedule having to “defend” their previous year’s April winning streak.  Or if your favorite football team started the season seventh in their division.  This is essentially what happens when the ATP heads to Australia in January, altering rankings only when players do something different than what they accomplished last year.

Not only does this make it hard too root for underdogs in tennis, it makes it hard for the underdogs themselves.  You may not pity Bernard Tomic, but he surely spoke for many mid-pack players when he spoke about the mental challenge of defending points, not just beating world-class tennis players.  In other sports, hope springs eternal.  In tennis, it’s an immense struggle to crack the top 20 for a single week.

The greatest advantage of the Race is that it is so easy to understand.  Tomas Berdych reached the semifinals last week, so he gets 360 points.  Simple as that.  No comparison to last year’s totals, no concern about whether points are going on or coming off at a stagger from last year because of the Olympics, and–blessedly–nary a mention of zero-pointers.  Tennis rankings will always be more than simply incrementing the win column, but this is pretty close.

Bodo cites the unpredictability of the turn-of-the-century Australian Open as a reason why the Race didn’t catch on.  It doesn’t make sense to have Petr Korda atop much of anything, right?  In fact, that’s the beauty of it.  The 52-week rankings simply entrench the Big Four in our minds, while an emphasis on the race would make us think twice the next time a Korda, or a Marcos Baghdatis, or a Marin Cilic, makes a January splash.  Fans are smart enough to realize that leading the rankings early in the season isn’t the same as finishing at the top.

Some version of the 52-week ranking system will never go away, and that’s how it should be.  It’s purpose is to rate players–for seeding, and even more importantly, for tournament entry.  As I’ve written at length, it’s not a very good system for that purpose.  If we focused on the Race instead, the tournament entry methodology could become much more sophisticated and do a better job of putting the best players on court every week.

With its increasing focus on qualification for the Tour Finals, the ATP has taken some big steps toward presenting tennis as a high-stakes, year-long season, not merely a disjointed mishmash of events competing for attention.  Highlighting the Race rankings would make for much more spectator enjoyment.  It might even open the door to more important discussions of the chaotic tour schedule, eventually offering fans a coherent tennis season to follow every week.