Posted by: Chris O'Leary (chris@chrisoleary.com) on Thu Feb 22 12:16:12 2007

"Try this clip, are you saying that there isn't a force directed down the length of the bat as well as the bat rotating?"

I would argue that what you are seeing when the bat is in the lag position is a consequence of the relative weakness of the muscles of the hands, wrists, and forearms. They aren't strong enough to maintain an angle other than perpendicular to the direction of travel as the shoulders start to rotate. Notice how in Pujols' swing the bat doesn't start to fly out over the plate until the shoulders start slowing down.

The same thing happens when a pitcher's shoulders start to turn. Their PAS upper arm externally rotates and their forearm lays back 90 degrees. The PAS elbow then rapidly extends as the shoulders start to decelerate.