Stu Woo, writing for The Wall Street Journal:
Fans live for long points. But exactly how much action is there in a tennis match? We took a stopwatch and timed two matches at the U.S. Open last week to find out. The answer: Not as much as you’d probably think. In the two matches we studied, only 17.5% of the time was spent actually playing tennis.
Baseball and football are played at an even lower percentage.