Alexander Zverev Jr. hits tennis balls as clean and as hard as anyone. His serve booms and his anticipation makes it tough to hit the ball by him. Most unusually, however, he moves with the grace of a man much shorter than his 6-foot-6 height.
Tennis has grown a lot during the Open era, which began in 1968. But the super tall—men 6-foot-6 or more—have been limited in performance. Juan Martin del Potro, the often-injured 28-year-old, is one of two men in that era to win a Slam at 6-foot-6 or taller, back at the 2009 U.S….