4 Top men’s serves often reach speeds of 125–135 m.p.h., true, but what all the radar signs and graphics neglect to tell you is that male power-baseliners’ groundstrokes themselves are often traveling at over 90 m.p.h., which is the speed of a big-league fastball. If you get down close enough to a pro court, you can hear an actual sound coming off the ball in flight, a kind of liquid hiss, from the combination of pace and spin. Close up and live, you’ll also understand better the “open stance” that’s become such an emblem of the power-baseline game. The term, after all, just means not turning one’s side all the way to the net before hitting a groundstroke, and one reason why so many power-baseliners hit from the open stance is that the ball now is coming too fast for them to get turned all the way.