The first champion to analyse his game mathematically seems to have been the American Jack Kramer. His method was simple. He had calculated his probability of winning each shot and used these percentages to plan his patterns of play. Naturally, this "percentage tennis", as it is generally known, also takes the opponent's strengths and weaknesses into account. Kramer therefore systematically used serve-and-volley tactics on both his first and second serves. In other words, percentage tennis is not the cautious, risk-free game some amateurs think they are playing. Each player should play the style of game they play best and that causes their opponent the greatest difficulty. If the opponent has poor movement, why not make them run by playing a ball that lands just behind the net?
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A few percentage points more… --------------------------------
As a simple example, let us consider the advantage of winning 60% rather than 55% of serve-and-volley points—a difference that may seem negligible and may even be difficult to notice without a scientific approach. This means winning at least 60% rather than 55% of one's service points. To analyse the question mathematically, imagine, once returns of serve are included, that each game is won with a probability of 60% rather than 55%. What effect does this have on a set? On a match? A probability calculation provides the answer. This calculation is the basis of percentage tennis!
In tennis, the rules are designed to magnify differences. To see how, imagine a match between two players, A and B. Suppose A has a 60% chance of winning each point. What is the probability that A will win a game? A set? The match? Answering this question requires an understanding of tennis's strange scoring system: 0, 15, 30, 40, then advantage or deuce, and game. This curious arithmetic conceals a simpler rule: to win the game, a player must win at least four points and lead the opponent by two. Under this rule, there are only so many ways a game can unfold. Every path begins at 0–0 and ends with one player or the other winning the game.