The Milwaukee Brewers’ first big trade of the 2025–26 offseason sent outfielder Isaac Collins and reliever Nick Mears to the Kansas City Royals in exchange for southpaw Angel Zerpa. Matt Arnold likely made this move due to his team’s crowded outfield, anticipating possible regression from Collins, who was a surprise Rookie of the Year candidate, and recognizing that Mears has no minor league options remaining, which limited his roster flexibility.
While the return may be a relatively unfamiliar 26-year-old former starter turned reliever, Zerpa has found modest success at the major league level over the past five seasons, posting a career 3.97 ERA. He has steadily earned higher-leverage opportunities over each of the last two years, recording 26 holds during that span, and he passes the eye test with ease, featuring a sinker that touches 99 mph and a wicked slider.
Here, we examine two additional metrics that suggest Zerpa may have even more to unlock with the Brewers, potentially elevating him to another level as a pitcher.
Two Angel Zerpa metrics that suggest he has massive upside as a member of the Milwaukee Brewers
1) Stuff+
The metric Stuff+ evaluates only the physical characteristics of a pitch. Key inputs include release point, velocity, vertical and horizontal movement, and spin rate, among others. A score of 100 represents league average, with anything above that indicating performance that percentage better than the norm. In 2025, Zerpa posted a Stuff+ of 117, tying for the highest mark in the league from a season ago, coincidentally matching Brewers reliever Abner Uribe
2) Spin rate
In baseball, spin rate is measured in revolutions per minute (RPM). Because Zerpa releases the ball more quickly than nearly anyone in the league, resulting in minimal extension, he generates elite spin on his pitches, particularly his slider. Last season, Zerpa’s slider averaged more than 2,600 RPM, good enough for having the ninth highest active spin on that pitch in the league.
Angel Zerpa is a sinker-heavy, ground ball pitcher. 96th percentile in GB%.
However, I’d like to see more of the slider as a K-pitch in ‘25.
Only threw it 26% of the time compared to his sinker being thrown 43.3%.
Slider had a spin rate of 2545. Up from 2418 in ‘24. #Royals pic.twitter.com/XQIUfST3p3
— Jack Johnson (@JohnyJ_15) November 13, 2024
When viewed together, Zerpa’s elite Stuff+ and top-tier spin rates suggest there is still more for him to unlock as a pitcher. The raw ingredients, premium velocity, exceptional movement, and elite spin, are already present, and those traits tend to age well and scale with refined usage and sequencing. In an organization known for maximizing pitching talent, the Brewers appear well-positioned to help Zerpa turn his impressive underlying metrics into even greater on-field results.
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