Yet the big difference between Burnett/Molina and Burnett/Posada during the regular season stemmed from Burnett’s much higher K rate with Molina (26.7% of batters) than with Posada (18.2%). And this was over hundreds of PA’s in each case. The BB rates for the two catchers were almost equal.

Explain the difference in K’s and I think you explain the difference in Burnett’s performance. I have no theory myself.

I’d have to invoke the sample size issue on your conclusion on Molina. Can we be sure Molina didn’t help him? I’m not saying I know…in fact, I don’t think we can really know, it’s too hard to figure out what, if anything, a catcher does for a pitcher.

Yes, this is my point. Burnett failed at controlling the things over which he has the most control: giving up free baserunners vs striking guys out.

“Yes, there is randomness in where the ball goes, but anyone who has watched Mo induce thousands of weakly squibbed grounders and little flares has to know that the pitcher definitely has an effect on the way the ball is hit. It may not be easy to extract from available data, but it’s there to a degree.”

Again, yes, I know the pitcher has some modicum of control over this…basically, whether the ball gets hit in the air or not and, perhaps, the field to which the ball is hit. And, the better your control, the more likely you can impact batted ball types and BABIP. And Burnett is a flyball pitcher with middling-to-poor control, which means that he’s not going to suppress scoring by suppressing SLG, and he’s not going to really be able to reliably impact where the ball gets hit. Which means he needs to strike guys out and avoid freebies as much as he can. And Molina didn’t help him do that _at all_ in his start in the ALDS, which shows there’s nothing magic about Molina.