CC Sabathia was the ace of the Yankees' pitching staff for four years, and his drop off in velocity in 2013 wasn't significant enough to have me worried earlier this season. Since then, he's added speed, and from June he's averaged around 92.5 mph on his fastball, which is very close to the 93 mph average in 2012. He's regained velocity, but something is still missing from the lefty. His recent set of abysmal starts has brought some serious concern about Sabathia and his long term future with the Yankees. As of today, he leads baseball in hits and home runs allowed, owning a 4.37 ERA on the season, his highest since 2002. So what's up with Sabathia? We know he's lost weight and he just underwent a somewhat minor elbow surgery, if you can ever consider elbow surgery minor. Back in May I suspected that he may be too healthy, and that his clean elbow and increased athleticism has added too much spin to his pitches. This is complimented by an increase in overall pitch movement since 2012, and this increase could throw off his command. Since then, Sabathia's movement has stabilized, and there isn't a significant difference in velocity or movement over his last few starts compared to last season.
Mechanically, Sabathia also looks like the same pitcher. There isn't anything too different from what he did in 2012 (left) and last night (right).
Even when placed on top of each other, Sabathia's mechanics and fastball movement look identical. (Red is 2013 and blue is 2012.)
So with PITCHf/x showing no significant signs of change and the video showing no differences in mechanics, I'm still left wondering what's up with Sabathia. There are a few splits that could mean something. Sabathia is giving up a ton of extra base hits while behind in the count. According to Brooks Baseball, Sabathia has thrown more four-seam fastballs than last season with the batter ahead, but relying on your fastball in this situation is typical of any pitcher.
The split that I find most interesting is what he does with men on base and in high leverage situations. For the most part, these moments come while Sabathia is in the stretch, and thus he has a different delivery than with the bases empty. Batters are hitting just .245/.293/.415 with the bases empty, but with men on, they're hitting .288/.329/.496. Sabathia is giving up more hits and extra base hits while in the stretch.
After last night's game, Chris Stewart talked about how Sabathia was leaving pitches up in the zone, and perhaps this has something to do with his bad numbers while in the stretch. Changing deliveries throughout a game can do a number of things to your mechanics, particularly your repetition and timing. A new age of scouts believe that the windup should be dumped entirely, and pitchers should deliver out of the stretch the entire game to maintain their timing. Yu Darvish has done this to much success since his introduction to MLB last season, and some believe pitching without a wind up is the future of baseball.
Obviously Sabathia has a history of success pitching out of both the windup and stretch, so it's not as simple as telling him to just stop using a certain delivery. Rather, there are clear issues when Sabathia has had to pitch out of the stretch, and though correlation does not imply causation, it's easy to see how timing issues in the stretch could be causing control problems and leading to those meat balls we've seen with men on base.