Sure, and he makes this point right there in TFA: "This observation applies only to amateur tennis. In professional tennis it’s just the opposite: 80% of the r

Sure, and he makes this point right there in TFA: "This observation applies only to amateur tennis. In professional tennis it’s just the opposite: 80% of the rallies are won rather than lost, as unforced errors are infrequent. This is true in chess as well, as high-level players don’t blunder, and thus it really is that litany of other skills that results in high standing."