The Second Serve Problem

The numbers look conspicuous to me. "If they get their first service in, itself a 65%-ish probability for a top player, they will win the point with a roughly 75% likelihood." implies a probability of winning the point on first service of just under 50%. Add in the "only 50%-ish of the time" for the second service and the 0% for the 3% of double faults, and I do not see how top players can win so many of their service games.

It still could be valid data for the whole set of professional tennis plagers (male and female), but I doubt one draw conclusions for individual players from it.

Tennis is not about winning individual points, but about stringing points together to win games (and sets). I find that first-serve faults tend to happen a lot in the same game. I think employing this "two first-serves" strategy and double-faulting a few times in a game could cost you a break of serve and lose you the set. Winning more points on average over the course of the entire match doesn't necessarily help.