Quirks of Pro Tennis Players Such as Bouncing Ball 30 Times Before Serving

“What I concluded was that the between-point time was a very fertile opportunity to get completely distracted and off course,” Loehr said. “The more time you have that you’re not doing something constructive, the more time you have to do things that absolutely allow you to drift, and what the better players do is learn how to fill that time with things that sequentially help them deal. It’s their countdown to launch.”

http://www.nytimes.com/2008/06/21/sports/tennis/21tennis.html