The Point After a Second Serve

Here’s a hypothesis for you: First serves are streaky.

It seems unquestionably true for amateurs. Our serves start clicking, or more commonly, fall apart entirely. Pros, though, are built different. After untold thousands of serves in practice, they should be steadier. The question, then, is whether they exhibit any streakiness at all, whether one missed first serve makes it more likely that they’ll miss the next one as well.

We can test this with the ever-growing dataset that is the Match Charting Project. Across over 4,000 charted men’s matches since 2020, the effect of one missed first serve on the next first serve is basically … zero. Not exactly: Men might be very (very) slightly anti-streaky, meaning that they are more likely to land a first serve on a point after a first-serve miss. But the effect is indistinguishable from zero, and the natural yo-yo of alternating deuce and ad courts erases anything that’s left. Some players have different results on the deuce and ad sides, so they are more likely to “recover” from a miss simply because they get to switch back to their preferred serve direction.

A few individual men show up as more streaky (or resilient, to use a more pleasant if less precise term for “anti-streaky”) than the norm. In the 2020s data, Novak Djokovic comes out as one of the most streaky, while Carlos Alcaraz scores among those at the other end of the spectrum. The magnitude, though, is tiny: We’re looking at shifts of about one percentage point in first-serve-in rate after a missed first serve. There’s not even enough data to be sure there’s an effect at all. Even if there is, that one percentage point translates to about one extra missed (or made) first serve every four matches, on average. It’s certainly not something you could detect by watching a match, or even a full tournament.

The story is somewhat different for women. Again using Match Charting Project data from the 2020s, spanning another 4,000-plus matches, we find that women make more first serves than expected on the point after they miss one. “Resilient” or “anti-streaky,” it doesn’t hold for every single player, but it’s a clear trend across the tour. As with the men, deuce/ad explains some of it, about one-fifth of the overall effect. What about the rest?

It would be one thing if there was simply no streakiness: We could give credit to the players for having trained themselves to the point that they are human ball machines. Maybe there’s something psychological, where players see a mistake, make adjustments, and temporarily become even better servers than their typical selves. More likely, though, it’s tactical. My instinct is that the average woman’s first-serve rate goes up because, having just missed a first serve, she becomes more conservative.

The evidence supports my guess. On first-serve points after a first-serve miss, women win 0.3 to 0.4 percentage points less often, compared to other first-serve points within the match. It’s possible that the additional lost points don’t stem directly from serve tactics, but the persistence of the effect points strongly in that direction.

We can even be a bit more specific. The difference is not speed: I checked the first-serve speeds after first-serve misses from Wimbledon and the US Open between 2021 and 2024. Controlling for serve direction, women served just as hard on those follow-up points, possibly even a tiny bit harder. If the point-outcome data can be trusted, the conservatism comes from serve placement, not direction (wide/body/T) or speed.

The net effect of all this is basically neutral. It’s good to decrease the odds of another second serve, but a slightly weaker first serve reverses some of that benefit. After missing a first serve, women servers win points at about the usual rate.

Double faults

Everything we’ve seen so far is a tiny effect, and it’s virtually no effect for men. The psychological or tactical shift is a bit clearer when we shift from missed first serves to double faults.

After a double fault, both genders dial things back with their next first serve. Men drop about 0.25mph from their average first serve. Roughly half of that comes from picking safer targets: They are less likely to fire one down the T, where margins are smaller. Women show a much bigger effect, dropping just over 1mph from their first serve. More than half of that comes from the direction. They, too, opt for body or wide serves as they seek to get things back on track.

Here, the results are far from neutral. There’s some degree of momentum regardless of which serves go in. Both men and women are a bit more likely to win a point after winning the previous point. But a double fault is recognizably different than a point lost by other means. The average woman’s first-serve winning percentage drops by almost a full point after a double fault, compared to other ways they could have lost the previous point. A couple of studies of mine suggest that 1mph in serve speed will move first-serve win percentage between 0.2% and 0.5%. So serve speed explains part of the win-percentage drop after double faults; other manifestations of serve caution, like placement, may account for the rest.

The men’s serve-speed drop is much smaller, so it’s no surprise that the point-result effect is smaller as well. The data doesn’t allow us to be as confident about this one as a real effect, as opposed to just suggestively-oriented noise.

My initial hypothesis was wrong, but the investigation turned up some momentum (and anti-momentum) effects that are worth more attention. Should players try to keep their first-serve risk level steady, or is a conservative offering a good way to get back on track? Is it possible to go wide or to the body without giving up quite so much? Should returners lean more in that direction, knowing that a double fault could influence the next serve? Beats me!