On the Not Literally Venomous Patrick Corbin

The lowest ERA on the Diamondbacks right now belongs to Matt Reynolds. The lowest ERA on the Diamondbacks belonging to a pitcher who’s thrown more innings than a really long baseball game belongs to Patrick Corbin. Monday night, Corbin took the mound in Coors Field with an ERA of 1.52. He came away with an ERA even lower than that, and at present his ERA is the second-lowest in baseball among starters. Only Clayton Kershaw has Corbin beat — Matt Harvey, Shelby Miller, Felix Hernandez, and everyone else is behind him. And Kershaw’s allowed three unearned runs. Corbin has yet to allow his first.

It’s been a brilliant season-opening stretch for a guy who now looks to have been underrated in the past. To pick on Keith Law, here he is calling Corbin a back-end starter, and here he is calling Corbin a No. 4. To pick on us, here’s Corbin as a potential No. 3, and here he is as a potential No. 3 again. Previously, it was thought that Corbin’s ceiling would be that of a mid-rotation starter, perhaps. Already, he’s exceeding that, and I’m not blaming the prospect evaluators. Corbin’s just beating expectations, and that’s worthy of a deeper dig.

In case you’d forgotten, Corbin arrived in Arizona as part of the Dan Haren trade, which we used to think was lopsided in the other direction. He went with Tyler Skaggs, and Corbin was never thought of as a top prospect. There are a few lessons we could learn from this, but we can leave those for another day. Now it’s time to get you familiar with what Patrick Corbin is, today.

Maybe the least interesting baseball article of the week would be “Patrick Corbin isn’t going to sustain his 1.44 ERA.” You know that, because you aren’t a moron. But there’s no other way around it: we have to acknowledge that Corbin is going to allow more runs. So far, in terms of run prevention, Corbin has pitched like an ace. The numbers tell us that won’t keep up. Some numbers even tell us Corbin is the same as he was a year ago. I like to use Mariano Rivera as a baseball stat sanity check. Corbin isn’t going to keep stranding more runners than Mariano Rivera. He isn’t going to keep allowing a lower BABIP than Mariano Rivera. He isn’t going to keep allowing a lower rate of home runs than Mariano Rivera. Corbin isn’t Mariano Rivera, because nobody is, and the fact of the matter is that things are going to get worse, at least on the scoreboard. Yet that doesn’t mean Corbin isn’t good, that doesn’t mean Corbin isn’t improved, and that doesn’t mean Corbin isn’t worth writing about, right here.

Let’s get the basics out of the way. Here are details:

Age
23

Throws
Left-handed

Height
6-foot-2?

Pitches
Four-seamer
Two-seamer
Slider
Change

Last year, Corbin debuted and was fine. This year, he’s either a little bit better, or a lot of bits better, depending on how you interpret the data. Used to be people would talk about Corbin needing to develop a better changeup if he wanted to stick as a starter long-term. Something he could offer to right-handed hitters to keep them off balance. Instead, he’s leaning more heavily on his slider, and though the slider is said to be a pitch with extreme platoon splits, Corbin’s approach is clearly working for him. At least so far, the slider has been an effective offspeed pitch against lefties and righties alike.

Which isn’t to say that Corbin doesn’t have big splits. This year, his strikeout rate against righties is less than half his rate against lefties. But then, his rate against lefties is terrific, and his overall numbers against righties are more than acceptable. A left-handed starter doesn’t have to be outstanding against righties to make it. He just needs to be fine, and Corbin meets that mark.

Now, before we get to more on Corbin’s slider, I’d like to mention a couple other things. Just looking at pure xFIP, you wouldn’t think that 2013 Corbin is markedly different from 2012 Corbin. But we know that’s too simplistic, and this year’s Corbin is throwing about a mile per hour faster, across the board. That doesn’t guarantee a better performance, but it increases a pitcher’s margin of error. Additionally, Corbin’s rate of first-pitch strikes is up from 59% to 71%. That’s the highest first-pitch strike rate in the league this season, and a pitcher getting ahead frees up a variety of options. It puts the hitter on the defensive. Corbin’s been good about achieving something of an elevated position.

But now back to that slider, because that slider is incredible. That slider has made 2013 Patrick Corbin into what he’s been. Corbin threw 34 against the Rockies on Monday, and 15 of their swings missed. Rockies hitters couldn’t say enough about it, and there were reports out of spring training that Corbin was throwing the pitch with more confidence. I’m not entirely sure what that means, but Corbin came into the year believing in his slider as a true weapon, and that’s how things have played out. Looking at a couple images can reveal how Corbin has been finishing his slider better than he did a season ago. Corbin tries to put his sliders in the same places against batters of both handednesses. From Texas Leaguers, we see Corbin’s sliders in 2012 and his sliders in 2013:

I haven’t yet learned Dave’s little mouse-over trick, but Corbin has been burying the slider in and beyond the corner much more regularly. That suggests improved release-point consistency and improved snap, and in case you’re wondering what the slider actually looks like, hey look, more .gifs, of course there have to be .gifs. From the Monday night slaughter:

Lefties have seen the slider 28% of the time, and 38% of the time with Corbin ahead. Righties have seen the slider 19% of the time, but 34% of the time with Corbin ahead. In two-strike counts, Corbin has thrown almost half sliders, and that’s why sliders have led to 40 of Corbin’s 51 strikeouts. Corbin has yet to strike out a single righty with a changeup this season, and it hasn’t mattered. The slider’s been death, and we aren’t through talking about it.

Let us consider some telling slider PITCHf/x information:

2012: 39% sliders thrown in the zone
2013: 24%

2012: 52% sliders swung at
2013: 51%

2012: 55% sliders contacted
2013: 42%

Corbin has moved the slider out of the zone more often, but it hasn’t stopped the hitters from swinging just as much. It’s simply stopped the hitters from hitting it as much. Corbin’s slider has been one of baseball’s premier putaway pitches to this point in time.

Baseball Prospectus offers useful PITCHf/x leaderboards. As you can imagine, lots of individual pitches have been thrown at least 100 times so far in 2013. For example, Ivan Nova has thrown 108 curveballs. Jarrod Parker has thrown 180 changeups. Patrick Corbin has thrown 189 sliders. They’ve generated a whiff/swing rate of just about 58%. That’s the highest rate of any individual pitch so far in baseball, given a 100-pitch minimum. Put another way, through May 20, no regular pitch has been more difficult to hit than Patrick Corbin’s slider, which he uses well against both lefties and righties.

Some of that is because Corbin mostly uses the slider in strikeout situations. He seldom uses it to pick up an early strike. But lefties have whiffed 59% of the time, and righties have whiffed 55% of the time. If you want to know the biggest reason why Patrick Corbin is blossoming right now, it’s because his slider is making hitters make fools of themselves. It’s been a rare slider to dominate opposite-handed hitters.

You can see some similarities between Corbin’s approach and Madison Bumgarner‘s, or Derek Holland’s. Corbin might still benefit from improving his changeup, but right now there isn’t that need. Right now, he can all but rely on his fastball and slider, because his slider is unlike most others.

Without question, Patrick Corbin is going to start allowing runs more frequently. Without question, some people are going to interpret this as a “fade,” and he’s less often going to look like one of the most untouchable aces in the league. Patrick Corbin, probably, is not going to develop into a classic No. 1. But he’s already developed into what looks like a capable No. 2, and a No. 2 can look like a No. 1 for considerable stretches when he’s at the top of his game. Many of the questions people used to have about Corbin’s changeup have been answered. And as it happens, they’ve been answered by his slider. Corbin’s in possession of a dominant pitch, and a dominant pitch can take a guy a long way.