This explains the the movement of the none pitching arm, but why slap the thigh, why not pull it back and create a greater stretch reflex and thus produce greater force. Pulling it straight down and slapping the thigh creates no increased stretch of the pectoralis muscle, which in turn does not generate additional force. Pulling the arm back as opposed to straight down would increase the speed of the closing phase of the pitch which again would increase the speed of the pitch. In my opinion, slapping the leg is wasted movement and is done through habit. I feel that very few successful college pitchers use a slapping motion as part of their pitching style.
