It was pretty obvious that Oswalt struggled as a starter down in Texas last year, earning him a couple different assignments to the bullpen. I went through his pitchf/x data for the season to differentiate Oswalt's effectiveness in the two roles and found some evidence that he could still be a valuable piece coming out of the pen in 2013. In a small sample, Oswalt's fastballs missed bats about twice as often when he was coming out of relief (15.93% versus 8.39%). I believe this is a good sign for Oswalt, because he's relied heavily on his fastballs for success over his career (64.2% frequency, +132.5 runs).

https://docs.google.com/open?id=0B5pIzP28qdp-YWc5dVZJRXVrX00

http://i.imgur.com/DYFzm.png?1

Would Oswalt be worth pursuing? What should the Twins be willing to pay?

Coupla things...

1) To me, Oswalt has limited value as a reliever for the Twins. I'm not opposed to him, but I'm also happy enough going dumpster diving for relievers and hope for some finds. That's funny for me to admit, because last year I was very critical of signing Joel Zumaya because I felt like they needed to fill that role with someone they could count on. This year, I'd be happy with a Zumaya signing.

2) Where did you get this data? It's kind of cool.

3) I wonder if .8 mph (if I'm reading the data right) is really much of a difference for a pitcher that is moved to the bullpen. It seems every pitcher would show some jump, and without any data I would think a couple of MPH might be fairly average. For instance, as a reliever, he never threw more than 20 pitchers. It wouldn't be shocked if, even as a starter, his first 20 pitches had more mph than his next 20. (Though, it also wouldn't surprise me if the mph increased as he "warmed up". ) I guess my question is how that increase compares to other pitchers who did a split role like Oswalt did. I think Perkins, for instance, added 3-5 mph to his fastball as a reliever, though I could be remembering that wrong.

Yeah its normal for a pitcher who moves from the rotation to the pen to experience velocity gain and also to throw the fastball with greater frequency. +0.8 mph is somewhat unimpressive but for whatever reason, that gain plus better movement maybe, the whiffs went up.

I would consider these starters who are aging and experiencing velocity decline to be a subset of the relief pitching dumpster, even if they don't always like to think of themselves as relievers (yet). Brett Myers may be another guy, although it looks like the Twins would stick him back into a starting role.

I got the data from brooksbaseball via Oswalt's game log page on baseball-reference. The "Pitches" Column is linked to the pitcher/date page at brooksbaseball