Austin Gomber Has Adjusted to Life at Coors Field

Austin Gomber came to the Rockies by way of the Nolan Arenado trade back in January, but of the five players acquired by Colorado, he faced the most immediate pressure as the lone newcomer expected to contribute to the big league club right away. That may feel like a bit of misfortune for a 27-year-old pitcher simply trying to find a foothold on a big league roster after bouncing between Triple A and the bigs between 2018 and ‘20 while with the Cardinals. Being traded for a franchise cornerstone wasn’t his only bit of rotten luck; he now has to make half of his starts in Coors Field, a place that is far and away the worst pitcher’s park in baseball.

Of particular concern for Gomber was his propensity for fly balls. In 104 career innings leading up to the trade, he had a below-league-average 40.7% groundball rate — an outlier on a pitching staff that continually ranks near the top of the league in that stat. It’s clearly an organizational philosophy; the Rockies have only had one qualified starter over the last decade with a groundball rate under 43% (Tyler Anderson in 2018). Making the matter more interesting was the comment Gomber made back in February in an interview with The Athletic’s Nick Groke after being traded: “I’m not going to try to become a groundball pitcher. That’s not who I am. That’s not how I got to the big leagues.”

The Rockies seek out, or perhaps try to create, groundball pitchers because of what Coors Field does to grounders — or more specifically, what Coors Field doesn’t do to grounders.

The thin air in Denver and massive outfield at Coors don’t affect grounders the way they do fly balls. Those are dangerous in general, but at Coors, they turn the hitter into 2002 Barry Bonds. Keeping the ball on the ground is the one thing pitchers can do to mitigate the massive advantage that the environment provides the hitter.

Now with that firmly at the top of your mind, let’s fast forward to Gomber’s most recent start against the Padres.

In case you weren’t counting along, that was 14 groundball outs in one start, by far his career high and the third most anyone has had in a start this season. A recent surge in grounders has him 18th in baseball in GB% out of 60 qualified pitchers. That percentage translates to a 108 GB%+, meaning he’s 8% better than league average at getting grounders. Some pitchers have worked for years trying to get hitters to put the ball on the ground against them; Gomber seems to have waltzed into a good groundball rate without even trying.

Beyond just the groundballs, Gomber’s introduction into Coors Field has been nothing short of spectacular; he carries a jaw-dropping 0.95 ERA in his five home starts with only one homer allowed. His FIP at home (3.09) backs that up; while regression may be headed his way, his ERA (3.54), xERA (3.35), FIP (3.67) and xFIP (3.70) tell the story of a comfortably above-average pitcher.

How is he doing it?

When watching the GIF above, you may have noticed that the grounders weren’t all coming on one pitch type. Gomber has a four-pitch mix, and he got grounders on all of his offerings against the Padres — par the course for him.

His fastball has fourth percentile spin rate, so it’s not exactly the type that gives up a lot of elevated contact. The low spin rate allows for gravity to do more work; as a result, he has a launch angle well below the league average for four-seam fastballs (18 degrees). In fact, all four of his pitches have launch angles lower than the average for each pitch type. That’s certainly a recipe you want when pitching at Coors Field.

All three of Gomber’s non-fastball pitches have been good at getting grounders this year, and all have been above average by pitch value. His changeup is actually the toughest pitch for hitters to get under, which is interesting considering it has less vertical drop than his slider and curveball, although it does dip four more inches than it did when he debuted in 2018. It’s also slightly better than average at producing grounders and has been great at producing soft contact, with an impressive 84-mph average exit velocity. If you look at his pitch mix, you can really start to see how he has become a groundball guy.

By pitch value, Gomber’s fastball has been his worst pitch and the easiest for hitters to get in the air, even if it’s still better than most fastballs in that regard. In total, he’s throwing about 10 fewer fastballs per start, replacing them with sliders and changeups. The curveball usage has dropped a bit as well, something that is probably the result of Coors Field’s harsh effects on the pitch’s vertical movement, which takes away about 2.3 inches of drop, according to Adam Maahs’ research. The changeup in particular is something that has really become a weapon for him; he’s gone from using it only a handful of times per start to this:

In his last five starts, Gomber has thrown his changeup more than 20% in each of them. He’s falling in love with the pitch at a time when he’s also getting more and more grounders. It’s easy to see why he’s using it so much; when you look at the pitch value leaderboards, it’s been the fourth-best changeup in baseball on a per-pitch basis. He’s allowing a .154 wOBA on the pitch compared to a .368 wOBA on his fastball.

In totality, these changes have led to more than just an improved groundball rate. Relying more heavily on his slider and changeup has increased his overall swinging-strike rate from below average (9.7%) to just about average (11.1%). In fact, he’s 13th in baseball in CSW%, right alongside fellow changeup-wielding lefty Trevor Rogers and Cy Young contender Brandon Woodruff.

If that is not enough, Gomber is also limiting walks in a way he never has before, issuing just one in his last five starts. That’s quite an impressive run after holding a monstrous 18.4% walk rate through April.

Throwing his changeup so often isn’t having a negative effect on his ability to get strikes; it’s better than average at getting grounders and better than average at getting whiffs. It’s a nice-looking pitch, and when he’s locating it at the knees, it is downright nasty.

It’s no wonder he is pulling the string more often than ever. I’m curious to see where his usage settles in as the season goes on and after the league starts adjusting to a pitch they now know they must prepare for.

Two months into the post-Arenado era, Gomber has been nearly as valuable (1.4 WAR) as the perennial All-Star (1.7 WAR). Sure, some regression is on the horizon, but the process changes that have led to his breakout lead me to believe that he is capable of surviving in his new home.