If you are interested in the BABIP stuff, good article on the Baseball Prosectus site titled "How Does Quality of Contact Relate to BABIP?
". (Subscription req.)
This article is about using batting F/X to measure hit speed, and not surprisingly finds that harder hit ground balls are base hits more often than slower hit ones.
So, two pitchers can indeed have similar numbers of balls hit in play, and have quite different results in terms of how hard those balls are hit.