CC Sabathia and the difference three years make

Two days ago, CC Sabathia did something he has not done since April 7, 2013: he had a start without allowing an earned run. When I first saw that, I thought to myself, "Yes, he's been bad for awhile now, but he's had a few good starts in the last three seasons, right?" No, he really hasn't. In that span, he has had a 120 ERA- and 107 FIP-, and only eleven starters have a higher ERA- in that time. When you've been struggling that much, scoreless starts are hard to come by. From 2010-2012, in contrast, he had fourteen such instances, and it really shows how quickly his performance has deteriorated but what has has changed?

During this start in April of 2013, Sabathia faced Justin Verlander in one of the first games of the year, and he tossed seven scoreless innings; he allowed just four hits and three walks while striking out four. A lot has changed since then. Heck, even Verlander isn't the ace he was at that time.

The first thing that I think a lot of people would point to as a difference would be velocity, and if you chose that you'd be generally wrong:

Even though his velocity has decreased on the aggregate, his velocity as of now is very similar to where it was in April of 2013. His velocity picked up as the year went on, but as we all know, that didn't really help his issues. Even with an average velocity around 93 mph, he still had a 6.08 ERA after the All-Star break in 2013.

If you were to guess pitch selection, then in this case you'd be right:

For obvious reasons, Sabathia has tried to rework his repertoire in response to his struggles; he has tried to reduce his reliance on his fastball, and now his sinker is thrown at nearly the same rate as his four-seam fastball. Opposing hitters are at 164 wRC+ against his sinker, so it's puzzling as to why he would do that. The fastball still induces an abysmal 115 wRC+, though. Whatever he has tried to do with his pitch selection, it has had a negligible effect.

One thing, though, that could be telling is his mechanics. First, let's take a look at a pitch, one against Miguel Cabrera, back in that 2013 game:

Now, take a closer look at his release:

Now, look at a pitch from his most recent start:

And if you look closer, take a look at this release point:

They're actually pretty similar! But, this looks to be in spite of his knee. There have been many cases where his arm drops lower, but he actually does a nice job here of maintaining his release point to get the best downward plane. Even though the release point can be relatively consistent, one can see the difference in mechanics between 2013 and 2015. In the former, Sabathia is able to use his right knee as a pivot point; he then thrusts forward and rotates his hips to finish.

In 2015, though, the finish is not as strong. He lands on his knee, hits the release point, but then bails a bit in the final phase of his delivery. This robs him of some stability, some movement, and of course some velocity. Even though he is trying his best to push against whatever pain is in his knee, it's still an inhibition.

It has been a rough couple of years for CC Sabathia. He's had very poor numbers, he's been injured a number of times, and it all happened very quickly. In between his two very good starts in 2013 and 2015, a bit has changed. He has been able to stall the demise of his fastball velocity, changed his pitch selection, and he's tried to adjust his mechanics with a degenerative knee condition. That implies, though, that his knee condition may never improve. We may never see prime CC Sabathia again, but we can appreciate how much he has tried to stem the tide of his decline.