Yesterday, I introduced a method to separate “good tiebreak playing” from “good tennis playing.” For the most part, better players win more tiebreaks, but some guys win more tiebreaks than their general betterness would suggest.
That impels some questions: Why do those players win more tiebreaks than expected? Do they do so regularly? Is it their style of play? Is it magical tiebreak-fu? Is it possible to get through two paragraphs of a post about tiebreaks without mentioning John Isner?
Here are two hypotheses, which I will discuss in turn:
- Players who win more tiebreaks than expected do so because their game is suited to tiebreaks–which probably means that they serve particularly well.
- Player who win more tiebreaks than expected do so because, in some intangible way, they are very good at tiebreaks, perhaps due to clutch play, calm under pressure, or intimidation of their opponents.
The server advantage hypothesis
Earlier this week, I reported my results that players seem to serve worse (fewer aces, fewer points won) in tiebreaks than in the sets that preceded those tiebreaks. If everyone declined the same amount, everyone would win roughly the number of tiebreaks we expect of them.
But much more likely, some players do not see their serves decline in tiebreaks. Some might even improve in breakers. If they do, they outperform the average, and they win more tiebreaks than expected.
Another angle here is that for some players, a bit of serve decline doesn’t matter much. In last week’s match between Isner and Kevin Anderson, Isner won 79% of service points and Anderson won 77%. Nearly one in five serves for the entire match went for aces–imagine how many more were service winners. If both players served a bit more conservatively in the breakers, would we even notice? When Fernando Verdasco starts playing it safe, it’s impossible not to notice–and easier to beat him in a breaker. Perhaps that isn’t so for the likes of Isner.
These are appealing theories. (Especially to me–I thought them up myself and believed in them for several hours.) However, the numbers don’t bear them out. There is no consistent statistical relationship between big serving and outperforming tiebreak expectations. To take a few examples: Isner is a tiebreak monster–probably the best tiebreak-player of this generation. Pete Sampras and Roger Federer are also among the greats. Below average, though, are the likes of Ivo Karlovic, Sam Querrey, Marc Rosset, and Robin Soderling.
Let’s try another…
The intangibles hypothesis
If there is some intangible mental factor that causes some players to win more tiebreaks than they would otherwise, it’s impossible to test for that effect directly–if it were possible, it wouldn’t be intangible.
But, if some players had that tiebreak-fu, they would probably hold on to it for more than a single season. For instance, when Novak Djokovic won an impressive 19% and 16% more tiebreaks than expected in 2006 and 2007, respectively, we should have been able to assume that he’s really good at tiebreaks, then predict that he would continue to excel in breakers in 2008. Yet in 2008, 2009, and 2010, Djokovic barely outperformed average, winning 2% or 3% more than expected. Ok, so we have a new forecast for Novak in the new decade: just a bit more tiebreak-magic than others. Yet in 2011, Djokovic won 10% fewer tiebreaks than expected. He’s 9% below average this year.
Sometimes, these changes might be explained by confidence. But more often, they are just plain random. While a few players (including Isner and Federer) put up great numbers every year, the vast majority of the field fluctuates, seemingly at random. The year-to-year correlation for the population of players with at least 15 tiebreaks in two consecutive years (going back to 1991) is almost exactly zero. (Set the bar higher if you wish; still barely distinguishable from zero.)
If tiebreak-related intangibles were widespread, there would be some kind of year-to-year correlation. Perhaps a small number of players do have that magic, but for the purposes of most analysis, it is more accurate to assume that when it comes to a player’s overperformance in tiebreaks, his record one year has very little to do with how he’ll perform the next.
One tiny ray of light
This gets a bit frustrating after a while. It seems that something should turn up as the cause of tiebreak excellence. One simple stat does, to a small degree: number of tiebreaks played. In other words, the guys who play the most tiebreaks tend to be the ones who beat expectations in those tiebreaks.
The connection that immediately springs to mind (after serving prowess, which we’ve already discarded) is practice. The more match-court breakers you play, the better you become. Isner, Federer, Sampras–they spend more time at 6-6 than almost anyone, and their tiebreak records are among the best.
Of course, the causation could go the other way. Perhaps confidence in one’s tiebreak skills cause a player to be more comfortable going to a breaker. While Djokovic or Andy Murray would press particularly hard for a break a game away from a 6-4 or 7-5 set, Isner is comfortable cruising into a tiebreak.
It’s a minor effect (r < 0.2), one that doesn’t explain anywhere near the observed year-to-year variance in tiebreak under- and over-performance. But it’s something.
The implications of the luck of the tiebreak
What if overperforming or underperforming your expected tiebreak performance is, essentially, luck? Or more generally (and safely) speaking, what if it says little about you likelihood of being good or bad at tiebreaks in the future?
For one thing, it would have a major impact on forecasting. If tiebreak performance one year doesn’t predict tiebreak performance the next, players with extreme under- or over-performances one year can be expected to regress to the mean the following year. It’s unclear exactly what that would mean in practice, but if you take away Feliciano Lopez‘s five tiebreaks more than expected in 2011, you’re left with a player who probably isn’t ranked within the top 20. You would expect a decline as he stops winning quite so many breakers.
On a more practical level, these implications might aid the confidence of players with middling tiebreak records. If you’re Andreas Seppi, who has a career losing record in breakers, you might be excused for some negativity when you reach 6-6 against, say, Karlovic. But if you know your own poor record is only loosely related to your skills, and Karlovic’s record isn’t nearly as good as it looks, you might take a different approach. Indeed, Seppi underperformed tiebreak expectations every year from 2006 to 2011, but has won more than expected this season–including one breaker each against Djokovic and Isner.
There’s plenty more work to do here–calling a couple of popular hypotheses into question hardly puts the issue to bed. But if we’ve learned nothing else this week, it is that tiebreaks are not at all what they seem. The players you think are masters are often middling performers, and regardless of the conventional wisdom, the breaker is about a whole lot more than a big serve.