Mike Marshall, the 1974 National League Cy Young Award winner and an associate professor of physical education, most recently at West Texas A&M University, winds up and delivers an answer to this one.
When baseball pitchers with various length pitching arms apply the same amount of force, the ones with shorter arms actually achieve higher release velocities. The muscles of players with shorter pitching arms apply their force with greater leverage—so, in order for pitchers with longer arms to achieve the same release velocity, they have to apply a greater force.
To understand how this happens requires knowledge of how muscles move the bones to which they are attached.
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As with any human movement, an athlete creates a desired motion by first using some muscles to stabilize the position of one of the bones involved in the action. Then when muscles contract, he or she moves the bone, which is to be put in motion, closer to the one that is stabilized in relation to the body.
In baseball pitching, to achieve their maximum release velocity, a baseball pitcher "locks"—or, stabilizes—the bone in his upper pitching arm (the humerus) to the bones in his shoulder. Then, after rotating his hips, shoulders and upper pitching arm as far as possible toward home plate, he contracts the muscles that move the bones in his pitching forearm, wrist, hand and fingers straight toward home as powerfully as he can.
How fast these bones move toward home plate then determines the release velocity of the baseball. Because shorter forearm, wrist, hand and finger bones have less inertia to overcome, a baseball pitcher can move them faster through release. As a result, with the same amount of force applied, a baseball pitcher with shorter bones in his lower pitching arm can achieve higher release velocities.