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Austin Gomber expanded his arsenal

As a minor league starter, Gomber succeeded using a repertoire which featured three average or slightly better pitches. For the first month of his tenure in the MLB, however, he tried to play the part of a two-pitch reliever, complementing his fourseamer with a big curve and essentially scrapping his changeup.

While most pitchers “play up” out of the bullpen when they can rely on their best stuff, Gomber didn’t – his “best stuff” was the depth of his offerings. When he didn’t find success in a relief role and was optioned to Memphis, Derrick Goold reported that Gomber was tasked by pitching coach Mike Maddux to develop a slider.

The development of a slider would have two benefits. For one, it would give Gomber a pitch moving away from lefties, a piece he sorely lacked. In his minor league career up until June 2018, he allowed a .285 wOBA to lefties compared to a .275 wOBA to righties. The difference isn’t so much you’d label it a reverse split, but Gomber’s repertoire had the characteristics of a pitcher who’d allow a reverse split in the majors. If he stuck as a reliever, that reverse split would limit his situational effectiveness. A slider might neutralize those lefties. On the other hand, if Gomber could throw just an average slider, he’d expand on his biggest strength as a starter – the depth of his arsenal. Either way, Gomber was set to benefit in the long-term.

I should note that this month may not be the first time Gomber has experimented with a slider – Eric Longenhagen of Fangraphs observed Gomber “was either varying his breaking-ball shape or mixing in a slider in 2017,” while red baron of VEB saw “what looks to [red baron] like a little cutter” and BotB prospect guru Kyle Reis noted he “can put slider movement on his fastball.” Given those characterizations, though, I think it’s safe to say the slider wasn’t a pitch Gomber used often as a prospect. Considering we didn’t see it in his first MLB stint despite Gomber appearing exclusively out of the bullpen and often against lefties, it certainly wasn’t a pitch he ever gained comfort with.

*Clarification: I don’t know what Gomber calls his slider/cutter but I’m calling it a slider.*

By going back to Memphis and working as a starter, Gomber was able to stretch out again while throwing the in-progress slider more frequently with a specific goal in mind. When he came back, we saw it featured in the majors for the first time. He turned to it 23 times out of 90 total pitches and, as a result, his depth was on display: the fourseamer was his most frequented pitch (37 pitches) and the changeup was his least (12) while the curve and slider were mixed pretty evenly.

Being able to throw both a slider and curveball is a relatively unique ability. According to Pitch Info (as of Friday morning), only 37 pitchers this season have thrown both a slider/cutter and curve at least 10% of the time and have above average run values for each (minimum 30 IP). The concern for pitchers who use both is that, if they lack distinct profiles, the two pitches might merge into one less effective pitch. Luke Gregerson is a cautionary example for Cardinals fans.

With that in mind, I dove into Austin Gomber’s expanded repertoire. I charted all of his MLB pitches based on their horizontal movement and vertical movement, then colored them by velocity (blue is slower, red is faster) and sized the data points by spin rate (larger dot means larger spin). Since the Pitchf/x and Statcast data files don’t show a slider, I used the charted information to reclassify Gomber’s pitches as fourseamers, changeups, curveballs, or sliders. The shape of the dot corresponds with the new pitch classification.

Movements are from the pitcher’s perspective. A positive horizontal number indicates right-to-left movement and a positive vertical number indicates “rise” as compared to a spin-less ball. Data through July 28.

In the top left are Gomber’s fourseamers and changeups. The movement profiles are extremely similar which makes the changeup more deceptive, and the fastball/changeup pair possesses a 10 mph velocity gap that is favorable for generating whiffs. The curve has an 11-5 shape and gets a ton of vertical separation from his fastball and changeup. The new slider slots in between with something between a 10-4 and 9-3 shape; it’s about 5 mph slower than his fastball, 4 mph quicker than changeup, and 10 mph faster than his curveball. The slider is unique enough to add something substantial to Gomber’s pitch mix.

In the chart above, however, you can already see the risk that curve and slider might blend: the curveball’s core has moved up and left since the introduction of the slider, and there are a few outliers that fall somewhere in between the two clusters. There are even a few fastballs that look like hard sliders or cutters, which might be what Kyle referenced in the previously-linked writeup.

With the acknowledgement that Gomber is probably still trying to find the best grip and action for the new slider, he’ll need to make sure the pitches stay distinct from one another moving forward. If they’re all working in tandem, the resulting movement differentials might look like this:

Given the similar release points and arm action, Gomber can make things difficult on hitters. We can't really see the horizontal depth in the angle above, but Gomber now possesses four pitches at four different velocities with four different depths vertically and two or three different depths horizontally. None of these pitches rate particularly well by themselves, but they play up together. It’s the kind of weapon that’s tough to pinpoint when you’re looking at physical tools and has probably held Gomber back in those rankings and even in his trajectory through the St. Louis system.

Looking at the charts again, you’ll noticed that I used June 30th as the before-and-after cutoff date instead of his last start – that’s because Gomber actually debuted the slider on June 30th against Freddie Freeman when none of us were watching:

Down 10-0 in the eighth is a great time to experiment. Gomber experimented by throwing his slider. Judging by Freeman’s swing, he didn’t know Gomber threw a slider. No one did because, up until that pitch, he hadn’t.

Back in the Majors for his first start nearly a month later, we got a more extensive view of what Gomber’s new pitch looked like. Here’s a good one to hotter-than-hell Eugenio Suarez:

A couple innings later, Gomber got him again with a nearly identical slider:

Billy Hamilton wasn’t a match for the slider either, getting tied up for the strikeout:

We’ve seen the slider working against an elite (although surprised) left-handed hitter. It worked twice against a very good right-handed hitter and again versus a bad one. To Freeman and Suarez, Gomber executed the pitch how we typically think of sliders by starting it low in the zone before letting it fall below the knee. Against Hamilton, he executed it more like a cutter running in on the hands.

With a more horizontal shape, the pitch should tunnel well with both Gomber’s fastball and changeup as long as he matches the release points consistently. Here he was ending a long eight pitch at-bat with Phil Ervin using the fastball/slider combo:

It’s worth noting that Gomber’s release point shifted significantly (~12 inches) toward first base during his start compared to his previous appearances by moving over on the rubber. Shifting his position toward first would exaggerate the glove-side action on his pitches and especially helps the slider.

After just one month, the slider is far from perfected. When Gomber has missed with the pitch, he’s mostly gotten under the ball and left it up. Hanging sliders up in the zone definitely aren’t good, but he got away with it for at least one game and, after his excellent starting debut, earned time to refine his new offering.


Since Gomber pitched on Sunday Night Baseball after @cardinalsgifs and I had completed most of this work, I've included a comparison below of Gomber's full season pitch data (from above) to his July 29 pitch data. He threw the slider relatively often again and came in at 89-90 mph, which is a little harder than he'd thrown it previously.

You can see the curveballs from Sunday night continuing to creep toward the slider cluster and there's another fastball or slider that fell in between either of those pitch types. Blending pitches is usually a bad thing, so hopefully Gomber can get the two pitches consistently distinct from each other.

*Credit to Brooks Baseball, Fangraphs, and Baseball Savant for the data used in this post.*

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