Well, this actually broke a month ago, by Mike Fast at Baseballprospectus.com, but I just saw it. In a nutshell, Mike uses pitch data to show that pitchers and hitters influence the Horizontal Speed of the Ball off the bat. This metric is derived, if I’m understanding correctly, by dividing the distance the ball traveled by the time it takes to go that far. Hard hit balls get places faster, more softly hit balls get places slower. Pop ups, almost always outs, don’t go far at all and take a long time to get there. By virtue of some commonsensical tests, Mike shows that pitchers have some effect on how hard the ball is hit against them. This appears to be groundbreaking work that confirms and quantifies what all of sensed intuitively: That BABIP isn’t completely random for pitchers. Good stuff.