Whitlock is no tennis expert or athletic performance expert. As of June 2009, the WTA has Serena's weight listed at 150 pounds, so unless he got her to step on a scale in the last two weeks, he is just spouting off. Give credence to his performance theories when he coaches an athlete to her level of success.
There is a time and way to say everything - he clearly needs a tact coach.
Stop giving Uncle Ruckus pub.