Talk about resurrecting an old post…wow. I threw with a heavy A2000XLC in high school and a lighter Rawlings after that. After going to the Rawlings, I could not go back to the Wilson A2000XLC. It didn’t feel right. I could easily transition from heavy to light than from light to heavy, but I did not experience any change in velocity going in either direction.
As I mentioned before: the first order of business is getting pitchers to try out a new motion bringing the center-of-mass further forward before the front foot lands (as in a tennis serve where I first worked on this “physics problem” if you will). As the front foot is landing, the small weight has fallen to the end of its journey downward (thus exhausting its potential energy) and is now being thrown backward (kinetic energy) as the upper body pulls the throwing arm forward and down. With the weight, this turning force is greater just like in the pulling force of the trebuchet. The greater force translates into greater translational energy of the throwing arm; hence the exit velocity of the baseball is higher. An interesting effect: not only for the players (throwers) in the study, but also for myself as a former pitcher (who throws hard for an old man; despite various arm injuries). Certainly well worth trying if folks want the details.