Just before Wimbledon I wrote a blog post showing how the weird scoring system in tennis makes it more likely that the worse player will win a match there than if the scoring system were purely based on the number of points won.
For both men and women, the chances of the worse player are boosted most in absolute terms if a player who is strong on serve plays one who is exceptional.
In the US Open, which runs this year in New York from 27 August to 9 September, a tiebreak is played even in the final, fifth, set for the men, third set for the women. Under a tiebreak system, if the final set is tied in games at 6-6 the first player to reach seven points with a two-point advantage wins the match; at Wimbledon, the winner must win the final set by two clear games.
How does the US Open scoring system affect the chances of the worse player? It gives them even more of a boost.
For men, a player who is strong on serve playing against one who is exceptional will win 24.6% of the time at the US Open (23.3% of the time at Wimbledon) against only 15.7% of the time if the scoring were points-based. So his chances are boosted by 8.9 percentage points (7.7 percentage points at Wimbledon).
For women, a player who is strong on serve playing against one who is exceptional will win 27.4% of the time at the US Open (26.7% of the time at Wimbledon) against 23.5% of the time if the scoring were points-based. So her chances are boosted by 3.9 percentage points (3.2 percentage points at Wimbledon).
Many people would consider this small increase in unfairness to be a price worth paying to avoid a repeat of the six and a half hour marathon men’s semi-final between Kevin Anderson and John Isner at Wimbledon this year, in which Anderson won the final set 26-24 in games. That would include both the winner and loser of that match.
Perhaps it is time for Wimbledon and the other Grand Slam tournaments to follow the example of the US Open and have a final set tie break.