The Split Personality Pitcher

I always enjoy the mystery player A/player B game, so let's have at it. Here are two pitchers. See if you can figure out who they are:

Both pitchers are just under a complete season for a starting pitcher, but with wildly different stats. Pitcher A would be lucky to hang on as a fifth starter for most teams, while pitcher B would be an ace on two-thirds of major league teams.

So who are these two pitchers? A hint before I reveal - they're actually the same pitcher over the course of 2012 and 2013. Broken down as we usually look at pitchers, by year, the pitcher's stats look like this:

But, instead of breaking up the pitcher's stats by the two calendar years, I've broken them up roughly as follows: pitcher A is the player for the first half of 2012 and the second half of 2013, whereas pitcher B is the player for the second half of 2012 and first half of 2013.

Looked at this way, the player was two completely different pitchers for long stretches of time. For the two book-end halves, the pitcher was horrible; in between, he was dominant. What's strange about this is that the pitcher didn't just show dominance or ineptitude off and on throughout both seasons, but rather showed both for long stretches of time.

Which raises the real question here - what was Kyle Kendrick doing from mid-2012 to mid-2013? How did he pitch like an ace for those 172 innings compared to the intense struggles in the other 169+ innings?

Without going into game tape, I certainly don't have the answer, though the BABIP column may provide some insight. Kendrick's career BABIP is .289. When he was pitcher A, his BABIP was .050 higher than his usual; when he was pitcher B, his BABIP was .033 lower than usual. So was he just luckier than normal for 172 consecutive innings from mid-2012 to mid-2013 and unluckier than normal for the half seasons before and after? Or was something else going on for Kendrick in those two stretches?

If the Phillies and Kendrick want to figure out a way to get a fourth top-notch pitcher on the mound following Cliff Lee, Cole HAmels, and A.J. Burnett, they need to do the work comparing these two stretches. If Kendrick was doing something from mid-2012 to mid-2013 that was different than the start of 2012 and end of 2013 (other than getting lucky), figuring it out is key.