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Know Your Orioles 40-man: Bruce Zimmermann

The hometown kid was a serviceable back-end starter when healthy, despite troubling peripherals. Can he stick in a big league rotation for a full season?

Boston Red Sox v Baltimore Orioles Photo by Mitchell Layton/Getty Images

This article is part of the Know Your Orioles 40-man series, which features an article about each of the 38 players currently on the Orioles roster. There will be one every weekday until we run out of players.

For any baseball fan who grew up fantasizing about playing in the big leagues for their hometown team, Bruce Zimmermann is living your dream right now.

The left-hander, born in Baltimore in February 1995, is the 27th Marylander ever to play for the Orioles, and just the 11th born in the city proper. His statewide baseball journey took him to Towson University and then — after a sojourn to the University of Mount Olive (N.C.) and a stint in the Atlanta Braves’ organization — returned him to his old stomping grounds when the O’s acquired him in the Kevin Gausman trade in 2018.

After a two-game debut in the bigs in 2020, Zimmermann was one of the most impressive stories of spring 2021, forcing his way into the Birds’ Opening Day rotation by throwing nine scoreless, one-hit innings in his first three outings of Grapefruit League play. He started the third game of the regular season and earned his first big league win to complete an opening sweep in Boston. Zimmermann ultimately made 15 appearances (14 starts) and posted a 5.04 ERA and 91 ERA+, which, considering the low bar set by the Orioles’ pitching staff, made him the second-best starter on the team behind John Means.

If this were a movie script, the hometown hero would continue to improve and eventually lead his favorite childhood team to World Series glory. In real life, that part seems improbable. While the Orioles have built a top-tier farm system (recently ranked #1 in baseball by ESPN) that could transform the team into a contender in the not-too-distant future, there might not be a place for Zimmermann on such a team. His modest 2021 statistical success belied some concerning peripherals that suggested he wasn’t fooling many hitters.

Per Statcast, hitters’ average exit velocity against Zimmermann — 91 mph — ranked in the worst 6 percent of major league pitchers. His maximum exit velocity (119.3) was in the worst 1 percent. His expected batting average (.294) and expected slugging percentage (.531) landed him in the bottom 3 percent and 2 percent, respectively. Hitters squared him up particularly well on his fastball, on which he allowed a painful .392 batting average and .711 slugging percentage.

Perhaps it’s no surprise, then, that Zimmermann tried not to be too reliant on his heater, throwing it 42 percent of the time while mixing in three offspeed pitches — a changeup, slider, and curveball. It was the latter two pitches, in particular, that brought Zimmermann success. Hitters slugged just .250 against his slider and a miniscule .167 against his curve. Though he threw each of them less than 20 percent of the time, they were his two most effective put-away pitches.

Zimmermann’s secondary offerings may be major league caliber, but you can’t succeed as a big league pitcher on offspeed alone if you don’t have a decent fastball to play off of. In 2021, that fastball was simply way too hittable, and Zimmermann was fortunate the damage wasn’t worse. Statcast measured his expected ERA at 6.39, well over a point worse than his actual ERA of 5.04. If his future performance trends further toward his problematic peripherals, it’ll be tough for Zimmermann to stick in the majors much longer.

Still, don’t count out the 27-year-old. He was never a top prospect coming through the Braves’ or Orioles’ minor league systems, but managed to succeed at every level thanks to his pitchability and above-average spin rate. He also flashed a competitive fire that not every major league can boast. Despite missing significant time with injuries last year — first, left biceps tendinitis that landed him on the IL in June, then a right ankle sprain during his minor league rehab that delayed his return — Zimmermann kept working, ultimately rejoining the Orioles in the season’s final week. His final two appearances were nothing special, but the fact that he’d battled his way back to return to a 110-loss team, when he could have just as easily packed it in for the year, says something about his desire to contribute to his hometown club.

End-of-season prediction: With all due respect to Zimmermann, it would be nice if he weren’t in the Orioles’ rotation by the end of 2022, simply because it would mean the O’s found five better starters than him. I’m not sure that’ll be the case, even if Grayson Rodriguez and D.L. Hall have joined Means in the rotation by year’s end. One way or another, I see Zimmermann finishing the season in the majors, either filling out the rotation or working in long relief. His iffy peripherals and limited ceiling means he won’t be a part of the Orioles’ future core, but he can be a useful enough arm to soak up some innings while the Birds’ more highly regarded pitching prospects begin to arrive in the majors.

Previously: Félix Bautista, Logan Gillaspie, Isaac Mattson, Cionel Pérez, Bryan Baker, Rougned Odor, Joey Krehbiel, Tyler Nevin, Kyle Bradish, Rylan Bannon, Yusniel Díaz, Kelvin Gutiérrez, Kevin Smith, Terrin Vavra, D.L. Hall, Jahmai Jones

Tomorrow: Mike Baumann