Carlos Carrasco’s most extreme week

Carlos Carrasco is a very good pitcher. Hell, he's a great pitcher. In 2017 he was 6th among starters in WAR, 12th in ERA, 10th in strikeout rate and walk rate, and hit 200 innigns for the first time. It was great to watch, he was just dominant, and consistently so, all year long. August was a weird month for him though. In the span of 10 days covering three starts, Carrasco had perhaps his worst and his best start of the season. In a season of near-constant excellence, this was Carrasco at his most extreme.

The second half was very good for the Indians righty. His ERA dropped from 3.44 to 3.12, he struck out more batters and walked less on a rate basis and gave the Indians depth, averaging 6 1/3 innings per start. But even those great numbers are skewed in so many ways by this stretch of 10 days. If I told you an otherwise ace caliber starter had a three game stretch where he averaged basically 5 innings a start with a 5.87 ERA, you'd likely point to that as the nadir of the season. And perhaps it was. For two of those three starts anyway. Carrasco's lines to open and close this short period couldn't be more different:

In short, that is Carrasco's worst pitched game (actually he had a game in late June with an 8 Game Score, but he at least lasted into the 4th inning) and his (tied for) best-pitched game. In between is a bit of an uggo, though he had only allowed three hits with seven strikeouts before the sixth inning went all to hell. In such a small time period, it's hard to draw any real conclusions. You'd think not much could change. Maybe he had a bad day. He certainly didn't keep the ball down against the Sox on the First:

Baseball Savant

That's a good recipe to get slammed. It could be as easy as that. However, if we look at what he threw from one game to the next:

Notice the rise of the slider from his stinker on the first to the sudden implosion on the sixth, to the gem on the 11th. Carrasco's slider usage as the year wore on dovetailed quite nicely with his excellence as the year wore on. In September when he threw it a quarter of the time, more than any other pitch, he had his best month with a 1.48 ERA, 1.71 FIP in 42 innings with 51 strikeouts. It's plain he realized something, and started leaning on it.

I had to look at each game, to see if each team had attacked him in different ways, and whether he was getting more first pitch stikes to get ahead, something like that. My findings:

Looking at his work on August First, it’s plain he was wild, which couples with his zone plot for the day. And it stands to reason that the more you can get ahead, the more success you have. By the 11th he was pounding the zone, they just didn’t have luck hitting the ball.

Adding to that, Carrasco may have made a mechanical adjustment. It seems minute, but he did start coming from behind his head a bit more, which could add some deception to his pitches. This GIF demonstrates the shift from before and after the 10th of August:

Baseball Savant

More specifically, this is where the ball came from on the First,

Baseball Savant

And the 11th:

Baseball Savant

Maybe not a sea change, but that's a definitive shift from one game to the next. It's hard to believe he started throwing like that right in the middle of the season of course. Mechanical adjustments like that don't just happen over night. Could it be that his slider comes from a different angle slightly, or he started coming more over the top to get more depth in it? These small shifts like this can mean so much.

It's a little stunning to think that one little tweak in the middle of the week was the difference for Carrasco between garbage and Mount Olympus. Is it really that much of a tweak though? Drastically shifting your pitch mix is something you can do from game to game, though changing your most familiar movement of your life even slightly can be a challenge That can throw everyone off, both opponents with scouting reports built up over the season as well as your own body. There's some credence to this though, his slider definitely got more drop as the year wore on:

This did happen with Justin Verlander when he went to Houston (or perhaps a bit before?) where he changed the delivery some to get more vertical movement, so maybe I'm underrating Carrasco's ability to make a sudden change.

It was a weird few days for Carrasco, literally his highest high and lowest low of the year. I've always thought he was capable of anything as a pitcher, and in early August he sure as hell proved that, for better and worse. He'd been so good before that collapse against Boston (which, objectively, was an amazing game despite that) it's neat to think that was a trigger point for him to make an adjustment that turned him into a worldbeater. May we all have such weeks.