The Resurgence of Pat Burrell
It appears to be that, in 2009, he was simply unable to hit soft pitches. As a Phillie, he had always been known for his ability to turn on an inside fastball. On the other hand, he was known for a “butt jut” on inside breaking balls. When he read the spin of an inside breaking ball, his feet would remain planted, but he would arch his back so that he almost looked like a backwards C at home plate.
In 2010, he regained his ability — or timing, most likely — to hit the soft stuff.
Pretty heat maps follow.