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Batters Can’t Stand This One Weird Pitch

Austin Gomber’s curveball is laying waste to the league. The scary part is, it still has room to improve.

Charles LeClaire-USA TODAY Sports

At some point, the Cardinals’ depth became a meme. You know the names of the opening day rotation. Martinez. Wacha. Wainwright. Weaver. Mikolas. Four months later, only Mikolas hasn’t been bitten by injury or ineffectiveness. The guys replacing them? Mostly, they’re just some guys. Jack Flaherty is somebody, an elite prospect made good. The rest? They’re essentially a human shrug emoji. John Gant has been on the periphery of relevance for years. Tyson Ross slipped right off the periphery and into irrelevance, but one of he or Daniel Poncedeleon, another guy who came from out of nowhere, looks likely to take a turn in the rotation soon. The guy who seems most unbelievable to me, however, is Austin Gomber.

Don’t take this the wrong way, but it’s hard to imagine a less likely prospect than Austin Gomber. Let me tell you some things about him. He was a fourth round draft pick- already, that’s long enough odds. About ⅓ of fourth round draft picks ever make the majors. Where did he go to college, you ask? Florida Atlantic, a school whose Wikipedia page lists as alumni Carrot Top, a professional video gamer, and the creator of PGP, but no athletes. That’s not exactly an awe-inspiring list. His scouting report coming out of the draft wasn’t exactly the stuff of legend- a lefty who sits 90mph and whose best pitch is a changeup isn’t a sexy pick. In his first year of low-A ball, he struck out 17.4% of batters he faced while walking 8.7%. Again, not blowing me away here.

As he progressed through the minors, his curve became his calling card. What did people think of that curve? Well, Eric Longenhagen of Fangraphs projected it as a 55 grade pitch (on the 20-80 scale) that could carry him to a fifth-starter profile. Our own Aaron Schafer? He was a little bit more positive on Gomber: “His curveball is probably his best pitch, and at its best I could see putting a 60 on it.” Well, that curveball is in the majors now, and it’s ridiculous. On at-bats that end in a curve, Gomber has allowed a .155 wOBA, a measure of overall offensive production where major league average is around .330. That’s the fifth-best result of any lefty with at least 25 at-bats ending in curves, just behind Blake Snell and Jose Alvarado, two devastating lefties with ERA’s in the twos and strikeout rates in the mid-20s. Think it’s a fluke? Per xwOBA, a measure of how likely the contact Gomber has surrendered is to become a hit, he’s still excellent, sitting at .233 xwOBA allowed. When Gomber throws a curveball, the league trembles.

This might be an oversimplified question, but uh, why? When I think of the best curveballs in the game, I think Aaron Nola or Rich Hill, Lance McCullers or Clayton Kershaw. What I mean by that is that I imagine the ball starting out at an absurd trajectory before diving across and through the strike zone. Basically, this:

You can almost see Anthony Rizzo’s soul leave his body on that pitch if you watch closely enough. Here’s the thing, though. That’s not what a Gomber curveball looks like. Let’s take a look at a similar called strike from last month:

It’s a little hard to tell from the camera angle, but there’s almost no left-right break in Gomber’s curve. In fact, of the 152 starters who have thrown at least 50 curves this year, Gomber ranks 24th-lowest in average horizontal break. Hm… curious. The rest of the indicators on his curveball are a bit mixed- he throws it with above-average spin and roughly average velocity; nothing too weird, but nothing outstanding either.

Now, if I told you that a pitcher threw a curve with below-average horizontal break and average speed, you’d say it was probably an average curveball. There is, however, one last dimension left- vertical break- and Gomber stands out there. In all of baseball, there are exactly four pitchers who have both a more negative vertical break and less horizontal break than Gomber- Clayton Kershaw, Robbie Erlin, Alex Cobb, and Chris Tillman. This is enlightening. First of all, it’s great to have your curve compared to Kershaw’s. Second, these guys have extreme 12-6 curves, which provides hitters a rare look. That weird look might feed into my favorite Gomber stat- batters have fouled off 42% of the curves they’ve swung at. They just can’t seem to time it very well. This deceptively up-and-down curveball does have a downside though- he’s induced whiffs on only 15.5% of swings, which is about as bad as it sounds.

So, okay, Gomber has a pretty unique curveball. It does most of its break vertically, and gets a good deal of spin relative to its speed. What are the implications of such a unique pitch? Well, first, 12-6 curves show a lot less of a platoon split than sweeping curves. The logic to this is pretty straightforward- a sweeping curve breaks towards an opposite-handed hitter’s bat, which gives them a tremendous advantage, whereas a 12-6 curve doesn’t move towards or away from the bat much at all. This lets Gomber use his best pitch against lefties and righties with equal effectiveness. The numbers on this? Gomber has allowed a .101 wOBA (.201 xwOBA) to righties with his curve versus a .212 wOBA (.266 xwOBA) to lefties. You should always be skeptical of reverse splits like this, but it’s encouraging to see that righties haven’t hit his curve at all.

Gomber’s dominance with curveballs has led to an overall reverse split- he’s allowed a .326 wOBA to lefties, meaningfully worse than the .289 he’s allowed to righties. It’s not just the curveball- Gomber’s fastball has been absolutely tattooed by lefties, which also weighs on the split- but the curve is a key feature of his mastery of righties thus far in his career. It could be even better, though. Here’s where he throws his curve to righties when it’s either a hitter’s count or an even count:

And here’s where he throws it with two strikes:

There’s just not enough separation between these two. The pitches out of the zone are easier to take with the hitter ahead, and the pitches in the zone are asking for trouble when the hitter is defending the plate. A little more separation in pitch mix could do wonders for Gomber’s already excellent results against righties. There’s one other pitch mix change I’d love to see Gomber make. Here’s a wonderful Brooks Baseball table that shows pitch usage for a ton of interesting splits:

Basically, he just needs to throw more curveballs to righties. The pitch works, and it’s pretty clear from both his scouting reports and his minor league numbers that he can spot it for strikes. I’d like to see him lean on it more for first-pitch strikes, hitter’s counts- really, I’d just like to see him use it more. There’s no real reason to throw so many sliders to righties, and with a curveball as good as his, there’s no real excuse not to emphasize the pitch more. Gomber’s curve is his best pitch, and it’s not particularly close. What’s wrong with throwing it 35-40% of the time and letting the chips fall where they may?

There’s a hidden, bad side to Gomber’s curveball dominance, I regret to inform you. He’s got a great curveball, as we covered above. His slider is death to lefties, and his changeup is totally serviceable against righties. Why, then, is he running a FIP above 4 and a walk rate of 12%, his highest at any level of professional baseball? Well, his fastball is bad, guys. Actually, bad might be the wrong term. It’s just not optimized. Gomber throws a four-seam fastball, and he’s added some serious velocity from the time he was drafted to now. In fact, of the 61 lefty starters who have thrown at least 100 four seam fastballs this year, he has the 12th-highest average velocity, 93.2mph. He pairs that estimable velocity with- oh boy. He pairs it with the fifth-lowest swinging strike rate among those same 61 lefties. What’s going on here? In a word, it’s the spin.

Now, there’s still a lot of research to be done on spin rate. Some of it is simply a function of how hard you throw. How much, exactly? Well, 5% of the variation in spin rate among lefty four-seam fastballs can be explained using their speed (my attempt to put R^2’s into words). The rest? We’re still learning! Some of it is innate. Some of it has to do with finger length and grip strength. It’s a mixed bag. One thing everyone can agree on, though, is that batters swing and miss more at high-spin pitches. The relationship between spin and whiffs is every bit as high as the one between velocity and whiffs. The race to throw harder, in other words, is also a race to throw with more spin. Austin Gomber lost that race. He has, you’ll remember, the 12th-highest average velocity among lefty starters. He has the eighth-LOWEST spin rate in that group. Gomber’s fastball defies the normal relationship between spin and speed in a pretty major way. The result? Hitters have teed off on his fastball this year.

This is a tough problem to fix. As I mentioned above, the source of spin rate is elusive. There’s one simpler fix, though. I’d like to see Gomber experiment with a two-seamer. Where high spin on a four-seamer produces ‘late life’ or the riding action that generates whiffs, low spin on a two-seamer gives it its signature sink. This is not a new observation, and I’m sure the Cardinals’ pitching coaches have discussed it with Gomber. Still, it’s a fix I’d love to see tried. We don’t have minor league pitch type data, but I wouldn’t be surprised if Gomber has just gotten by on his four-seamer his whole career due to how overpowering his curve is, and a fastball switch could unlock a totally different look.

Here’s the bottom line: Austin Gomber is an effective major league pitcher right now. That in and of itself is a crazy sentence, but let’s try a crazier one. Austin Gomber has the stuff to be an All-Star. I’m serious! He has one plus-plus pitch and two solidly plus pitches. His worst pitch, his fastball, is also the 12th-fastest lefty fastball in baseball. We could legitimately be two changes (curveball location and fastball type) away from Austin Gomber being a terrifyingly good lefty starter, the kind of guy who moves from depth meme to mid-rotation starter with upside to more. In a year, we could be talking about a guy with four plus pitches and excellent control. Move over, Carrot Top- we’re going to need your space on the famous alumni page.