Both the ATP and WTA patched together seasons in the second half of 2020, providing playing opportunities to competitors who had endured vastly different lockdowns–some who couldn’t practice for awhile, some who came down with Covid-19, and others who got knee surgery.
When the tours came back, we didn’t know quite what to expect. I’m sure some of the players didn’t know, either. Yet when we take the 2020 season (plus a couple weeks of 2021) as a whole, what happened on court was pretty much what happened before. The Australian Open, with its dozens of players in hard quarantine for two weeks, may change that. But for about five months, players faced all kinds of other unfamiliar challenges, and they responded by posting results that wouldn’t have looked out of place in January 2020.
The Brier end
My usual metric for “predictability” is Brier Score, which measures both accuracy (did our pre-match favorite win?) and confidence (if we think four players are all 75% favorites, did three of them win?). Pre-match odds are determined by my Elo ratings, which are far from the final word, but are more than sufficient for these purposes. My tour-wide Brier Scores are usually in the neighborhood of 0.21, several steps better than the 0.25 Brier that results from pure coin-flipping. A lower score indicates more accurate forecasts and/or better calibrated confidence levels.
Here are the tour-wide Brier Scores for the ATP and WTA since the late-summer restart:
- ATP: 0.213 (2017 – early 2020: 0.212)
- WTA: 0.192 (2017 – early 2020: 0.212)
The ATP’s level of predictability is so steady that it’s almost suspicious, while the WTA has somehow been more predictable since the restart.
But we aren’t quite comparing apples to apples. The post-restart WTA was sparser than the pre-Covid women’s tour, and the post-restart ATP was closer to its pre-pandemic normal.
Let’s look at a few things that do line up. Most of the top players showed up for the main events of the restarted tour, such as the US Open, Roland Garros, Rome, “Cincinnati” (played in New York), and men’s Masters event in Paris. Here are the 2019 and 2020 Brier Scores for each of those events:
Event Men '19 Men '20 Women '19 Women '20 Cincinnati 0.244 0.210 0.244 0.252 US Open 0.210 0.167 0.178 0.186 Roland Garros 0.163 0.199 0.191 0.226 Rome 0.209 0.274 0.205 0.232 Paris 0.226 0.199 - - --- Total 0.204 0.202 0.198 0.218
(If you want even more numbers, I did similar calculations in August after Palermo, Lexington, and Prague.)
Three takeaways from this exercise:
- Brier Scores are noisy. Any single tournament number can be heavily affected by a few major upsets.
- Man, those ATP dudes were steady.
- The WTA situation is more complicated than I thought.
Whether we look at the entire post-restart tour or solely the big events, the story on the ATP side is clear. Long layoffs, tournament bubbles, missing towelkids, Hawkeye Live … none of it had much effect on the status quo.
The predictability of the women’s tour is another thing entirely. The 12 top-level events between Palermo in July and Abu Dhabi in January were easier to forecast than a random sampling of a dozen tournaments from, say, 2018. But the four biggest events deviated from the script considerably more than they had in 2019 (or 2017 or 2018, for that matter).
From this, I offer a few tentative conclusions:
- Big events, with their disproportionate number of star-versus-star matches, are a bit more predictable than other tournaments.
- Accordingly, the post-restart WTA wasn’t as predictable as it first appeared. It was just lopsided in favor of tournaments that drew (most of) the top stars. Had the women’s tour featured a wider variety of events–which probably would’ve included a larger group of players, including some fringier ones–it’s post-restart Brier Score would’ve been higher. Perhaps even higher than the corresponding pre-Covid number.
- Most tentative of all: The predictability of ATP and WTA match results might have itself been affected by the availability of tournaments. Top men were able to get into something like their usual groove, despite the weirdness of virus testing and empty stadiums. Most women never got a chance to play more than two or three weeks in a row.
Even six months after Palermo, the data is still limited. And by the time we have enough match results to do proper comparisons, some things will have gotten back to normal (hopefully!), complicating the analysis even further. That said, these findings are much clearer than my initial forays into post-restart Brier Scores in August. As for the Australian Open, quarantine and all, I’m forecasting a predictable tournament. At least for the men.