Many players didn’t like the conditions at Roland Garros this year. The clay, apparently, was slower and heavily watered, at least on some courts. The balls were heavier than usual, especially when they had been in play for a little while and the clay began to stick to them.
Maybe the courts really did play differently. We could compare ace rate, rally length, or a few other metrics to see whether the French played slower this year.
I’m interested in a broader question. Were the conditions weirder? To put it another way, were they outside the normal range of variation on tour? We could be talking about anything that impacts play, including surface, balls, weather, you name it.
This is surprisingly easy to test. The weirder the conditions, the more unpredictable the results should be. If you don’t get the connection, think about really strange conditions, like playing in mud, or in the dark, or with rackets that have broken strings. In those situations, the factors that determine the winner of a match are so different than usual that they will probably seem random. At the very least, there will be more upsets. Holding a top ranking in “normal” tennis doesn’t mean as much in “dark” tennis or “broken string” tennis. While unusually heavy balls don’t rank up there with my hypotheticals, the idea is the same: The more you deviate from typical conditions, the less predictable the results.
We measure predictability by taking the Brier score of my Elo-based pre-match forecasts. Elo isn’t perfect, but it’s pretty good, and the algorithm allows us to compare seasons and tournaments against each other. Brier score tells us the calibration of a group of predictions: Were they correct? Did they have the right level of confidence? The lower the score, the better the forecast. Or put another way, for our purposes today: The lower the score, the more predictable the outcomes.
Conclusion: This year’s French wasn’t that weird. Here are the Brier scores for men’s and women’s completed main draw matches, along with several other measures for context:
Tourney(s) Men Women 2023 RG 0.177 0.193 2022 RG 0.174 0.189 2021 RG 0.177 0.194 2020 RG 0.200 0.230 2000-23 RG 0.169 0.184 00-23 Slams 0.171 0.182 Min RG 0.133 0.152 Max RG 0.214 0.230
(“Min RG” and “Max RG” show the lowest and highest tournament Brier scores for each gender at the French since 2000.)
Again, lower = more predictable. For both men and women, the 2023 French was no more upset-ridden than the 2021 edition, and it ran considerably closer to script than the zany Covid tournament in autumn 2020. The results this year were a bit more unpredictable than the typical major since 2000. But the metrics tell us that the outcomes were closer to the average than to the extremes.
However unusual the conditions at Roland Garros felt to the players, the weirdness didn’t cause the results to be any more random than usual. While adjustments were surely necessary, most players were able to make them, and to similar degrees. The best players–based on their demonstrated clay-court prowess–tended to win, about as often as they always do at the French.