What Magic Is Brewering for Milwaukee’s Newest Pitchers?

When the Royals traded for Isaac Collins in December, I praised the move. I understand that there are limitations to a 5-foot-8 corner outfielder who showed his first signs of major league life at age 27, but the man hit .263/.368/.411 last year, and the Royals — a team traditionally in dire need of live bats — only gave up a middle reliever to get him.

A Royals fan on Bluesky asked me how to feel about that move when it happened, and I answered thusly: “I think it’s a steal, as long as you make your peace with the small but non-trivial possibility that the Brewers turn Angel Zerpa into Josh Hader.”

The best thing a front office can be is self-aware, to know its strengths and weaknesses in scouting and development. Occasionally, a team will get so good at identifying diamonds in the rough that it turns into a meme. The Dodgers or Rays will sidle up to a team, offering to take a potential Rule 5 casualty or Complex league teenager off its hands. Like Mephistopheles, or a guy in an old-timey cartoon who sells cigarettes to kids out of his trenchcoat.

This got to happening frequently enough that it turned into a meme. If such-and-such a GM calls and oh-by-the-way inquires about a kid with 14 walks over 10 innings in Rookie ball, you not only hang up the phone, you also change your number and fake your own death.

Like all memes, the general truth of this joke is not universal, because developmental competencies are not the same team-by-team. The Dodgers at the height of their powers got swindled out of Yordan Alvarez, while the Rays were had by the Phillies twice in 13 months, for José Alvarado and Cristopher Sánchez. Still, don’t take the call, it’s too risky.

The Brewers are kind of in that space now. Their hitting development has its ups and downs, but they’re among the best in baseball at conjuring quality pitching from thin air. Of the Brewers’ top-10 pitchers in either ERA or WAR in the 2020s, only Brad Boxberger was drafted in the top 50 picks, and by the time the Brewers got their hands on him, they were able to sign him as a free agent for $1 million. Abner Uribe: $10,000 IFA signing bonus. Corbin Burnes: fourth-round pick. Brandon Woodruff: 11th-round pick. Freddy Peralta: acquired in a trade for Adam Lind.

I could go on.

The Brewers made three trades this offseason, each of which sent out at least one significant contributor from the 2025 major league roster, in exchange for prospects or young big leaguers. Collins wasn’t even the top Rookie of the Year vote-getter the Brewers traded this offseason; thanks, Caleb Durbin.

I was critical of each of these moves, from Milwaukee’s perspective, because the team with the best record in baseball last year was making itself worse, instead of doing whatever it took to get over the top.

But leaving that aside, the Brewers were up to something interesting. They were after a specific kind of player: mid-20s big league pitchers. Not prospects. You can dream on prospects. Prospects carry the alluring perfume of the unknown; a prospect can be anything. No, guys with at least some big league experience, enough to scuff up their paint. It’s the guy-with-a-trenchcoat-in-an-alley thing again: Hey, instead of giving up one of your fancy prospects, I’ll take this pitcher everyone’s nitpicking and see what I can do with him.

This isn’t new; the Brewers nabbed Quinn Priester from the Red Sox a year ago, and DL Hall in the Burnes trade from Baltimore the year before. If you have confidence in your player development system, you can take swings like this.

The three pitchers the Brewers got back — Zerpa, Kyle Harrison, and Brandon Sproat — all have above-average fastball velocity with a certain movement profile, an average arm angle between 27 and 33 degrees, and at least one weird pitch.

For Zerpa, all three of his primary pitches — four-seamer, sinker, and slider — have significant downward movement compared to similar pitches of their type and speed. Last year, Zerpa’s slider had the sixth-most drop above average, and the third-most induced vertical drop. You’ll never see a more crystal clear correlation between sinking movement and the effects of hitting the underside of bats; he had a second-percentile whiff rate but the fifth-highest GB% among qualified relievers in 2025.

Zerpa has spent most of this spring with the Venezuelan national team, for whom he’s thrown 4 2/3 scoreless innings at the World Baseball Classic. So the Brewers haven’t had as much of a chance to tinker with him in spring training. However, you can guess where Zerpa’s Milwaukee career is going pretty easily. Exactly one spot ahead of him on the slider movement and groundball rate leaderboards is another Brewers lefty: Aaron Ashby.

Ashby, a fourth-round pick out of a Missouri junior college, is a major middle relief weapon-cum-playoff opener for the Brewers. His ERA last year was half what Zerpa’s was, perhaps because his slider marries hellacious downward movement with equally fierce horizontal movement, while Zerpa’s goes straight down. Ashby was in the 63rd percentile for whiff rate and 84th for strikeout rate; if Zerpa can get swing-and-miss numbers like that, the Brewers won’t miss Collins that much.

Sproat is the most conventional of the three new Milwaukee pitchers. He’s a big right-hander with a five-pitch arsenal, recently drafted in the second round out of Florida, where he was a weekend starter on a team that played for a national championship. What is there to fix?

Well, Sproat’s throwing a little harder, though I wouldn’t read too much into velocity numbers when comparing September to March. That could be a genuine uptick in velocity, or it could be an artifact of Sproat’s being tired last fall. I do want to highlight one thing, but first I’m gonna need one of you to spot me a dollar to throw in the “He should learn a cutter” swear jar. I left my wallet in my other pants.

Sproat threw only 20 2/3 innings for the Mets last year, which is not enough to draw sweeping conclusions about the efficacy of his fastball mix against big league competition. But his most-used pitch was a hard sinker with wicked arm-side movement. Off that, he had a four-seamer with good velocity (average 96.7 mph) but a dead zone movement profile. He also threw 10 pitches that got tagged as sliders — which is not the same as his sweeper — that came in around 90 mph with neutral movement and don’t do much of anything for anyone.

So instead of the slider, the Brewers have him throwing a cutter that’s averaging 94 mph, with vertical movement that’s in between the four-seamer and sinker, but center line horizontal movement instead of arm-side run. Hopefully, it’ll give hitters something to think about when they see fastball.

But the pitcher I’m most excited about is Harrison. The former top Giants prospect has always had a fastball with goofy arm-side run out of a weird low arm slot, plus a slow two-plane breaker that Baseball Savant tags as a slurve. That’s a designation you don’t see much; until I was on Harrison’s page just now, I’m not sure I could’ve told you that Savant shows slurves in a pleasant periwinkle color.

Harrison has suffered the wrath of several sporting clichés during his brief time in the majors. You can’t get opposite-handed batters out from a low arm slot. You can’t be a starter without three pitches. And having been traded from San Francisco to Boston to Milwaukee in the span of eight months, he’s like a young quarterback who’s had a new offensive coordinator every year of his career.

He did make heavy use of an offspeed pitch in 2024. About 20% of his total pitches were changeups, with similar horizontal movement to his fastball, but eight miles per hour slower and with nine more inches of induced vertical break. It got crushed. In 2024, opponents posted a .328 wOBA and .358 xwOBA off the changeup, and Harrison relegated it to show-me status in 2025.

But man cannot live on slurve alone, so Harrison kept working. Curt Hogg of the Milwaukee Journal-Sentinel wrote two weeks ago about the evolution of Harrison’s changeup. He now throws a kick change, using a spike grip that’s become trendy over the past few seasons, instead of a traditional version of the pitch. Harrison toyed with it last year, but only got it to click this winter. Compared to the old changeup, this one spins about 300 rpm less, so it drops more — the difference to the four-seamer is almost twice what it was two years ago.

For all the insinuations I’ve made about Brewers pitching development magic, this is a tangible, non-magical thing Harrison seems to have figured out on his own. And while having those figures is certainly encouraging, his new changeup has yet to encounter its first meaningful opponent. So we’ll see.

Nevertheless, if a team wants to keep making the playoffs while consistently shedding its best players, it has to be both lucky and good at identifying its next generation of contributors. That much the Brewers have been able to accomplish.