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.