I just read this in the Tao of Jeet Kune Do (published 1975), immediately thought of you guys:
"after momentum in a throwing or elliptical striking movement has been generated by a long radius and a long arc in the swing, the speed may be increased without applying additional force by suddenly shortening the radius of the arc. this is seen in the "pull-in" at the last of the arc in the hammer throw, in the backward thrust against the forward leg by the batter in baseball, and so on. snapping a towel or a whip are common examples of the same "shortened lever" principle."
"after momentum in a throwing or elliptical striking movement has been generated by a long radius and a long arc in the swing, the speed may be increased without applying additional force by suddenly shortening the radius of the arc. this is seen in the "pull-in" at the last of the arc in the hammer throw, in the backward thrust against the forward leg by the batter in baseball, and so on. snapping a towel or a whip are common examples of the same "shortened lever" principle."