Over a match, we get an oscillating curve like this:
You may notice, it says Rating, faded momentum instead of just momentum. Let me explain that.
To not only rate a point made as yes or no, but instead take the way the point went into account, I rated the outcome from 1 to minus 1. 1 represents a winner or an ace, 0.4 was an opponent’s error, minus 0.4 an own error, -1 was a double fault.