Posted by: yesisbest () on Sat Feb 4 21:10:29 2006

Think about the definition of creating batspeed: creating the maximum possible amount of torque on the bat handle via the hands. (I'm not saying the hands apply most or all of this torque; rather, any torque created by the body must be transfered to the hands for it to have any effect.)

At the very end of the swing, the body must make any possible motion to create that last boost of batspeed without regard to its implications (since the ball will have left the bat by then). Straightening of the back arm is generally considered bad mechanics because it brings the bat around with only the arms rather than allowing the body to bring it around. At the last moment of the swing, however, the bat MUST get around. By using the shoulders (specifically, the lead shoulder) to pull the bottom hand and knob AWAY from the pitcher (counter-clockwise for a righty...just imagine it) at that last moment, the top hand is still left to do some work to create that torque. Instead of a simple uncocking of the wrists, why not push with the back arm to aid with that torque? Pushing of the back arm will push the hand "around" the bottom hand, which creates torque.

McGwire does exactly this:

http://www.pichut.org/up/macgif.gif