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Zac Rosscup was the forgettable Rockies hero

His big league mission may have been over before it began — but his Triple-A dominance should not go unnoticed.

Welcome to the 2021 edition of Ranking the Rockies, where we take a look back at every player to log playing time for the Rockies in 2021. The purpose of this list is to provide a snapshot of the player in context. The “Ranking” is an organizing principle that’s drawn from Baseball Reference’s WAR (rWAR). It’s not something the staff debated. We’ll begin with the player with the lowest rWAR and end up with the player with the highest.

★ ★ ★

No. 29, Zac Rosscup: 0.0 rWAR

If it weren’t for COVID-19, Zac Rosscup may have never made the big leagues this year.


Rosscup debuted with the 2021 Rockies on July 17. One day earlier, the Rockies had a run-in with COVID-19 that sidelined pitchers Yency Almonte, Jhoulys Chacín and Antonio Senzatela for about two weeks. With nowhere to turn and a strong reliever waiting in Triple-A, it was a necessity for Rosscup to join the big league club.

The 33-year-old Rosscup pitched only three innings with the Rockies this year, mostly a collection of low-leverage late-inning appearances. He spent 16 days in the big leagues, but disappeared back to Triple-A once Almonte, Chacín and Senzatela returned.

Rosscup got some work done in the big leagues, at least: 3 IP, 3 H, 1 R, 1 BB, 4 K. 3.00 ERA.

His body of work in Triple-A was a lot more substantial: 29 IP, 2.48 ERA.

Colorado’s bullpen ERA last season was 6.77, the second-worst figure in baseball, Their 2021 figure at 4.91 was the fifth-worst, and reliever struggles were a motivating factor in bringing on Rosscup in the first place. A rebuilding team with a few relievers in their mid-30’s (Bard, Chacín, Rosscup) wasn’t ideal for organizational development, but it helped bridge the gap for developing arms that may not have been ready for a bigger jump.

Rosscup was that Triple-A bridge, and he just so happened to taste a big league reward.

Raw Stuff: Better Than Before

A three-inning sample size of big league data is extremely limited, but some changes in spin suggest a rebranded pitch mix was able to yield impressive results. Baseball Savant says Rosscup didn’t throw a curveball prior to this year, and the average horizontal break on his slider was 2-3 inches different than his average from 2017-2019.

With a combined season ERA in the mid twos (between Triple-A and MLB work), the new mix seems to have worked for him. It may have been a necessity as his velocity declines. Rosscup’s fastball averaged 93.6 in 2015; it averaged 90.7 this year.

An Empty(?) Mission

After seeing the fate of Rosscup after his call-up, it’s easy to feel like his mission was over before it even began. He’s amassed four years of big league service dating back to his 2013 debut, but after dominating much of his 2021 schedule in Triple-A, his short-lived work in the big leagues suggested the Rockies were using him for minor league depth and little else.

(This was first reflected by the MLB club when Joe Harvey was called up and DFA’d before throwing a single big league pitch this year.)

Rosscup lived through indy ball in 2020, pitching for the Sugar Land Lightning Sloths before inking a deal with the Rockies that kept him at the 2020 alternate site. He didn’t have much of a choice when Colorado came calling: it was either accept the most minor of minor league deals, or potentially end his career with a team called the Lightning Sloths.

Rosscup’s work this year was pretty forgettable outside of Albuquerque, but it was formidable as an unsung hero. It’s a challenge to envision a future with him in the Rockies bullpen, but if the aging reliever was seeking one more taste of the big leagues, he got what he was looking for.