Now I want to take a turn towards momentum, trying to explain what happens within a match, to understand the patterns underlying these winners, errors, aces or double faults a tiny bit better.
One way is to find a number for a series of points happening in favor of or against a player, calling that the momentum.
Basically asking: How many of the last points did the player win? 5 out of the last 5 would be 100 percent, 0 out of 5 is a hard 0 percent.