Top 20 Brewers Prospects, May 2025 Update: Three New Names to Know

The Brewers farm system continues to impress, despite a number of big-time graduations over the last few years. The three new names on this list are just a few examples of the depth the system possesses. 

No. 13 - 2B Josh Adamczewski
The Brewers drafted Adamczewski in the 15th round of the 2023 draft and signed him away from a Ball State commitment. Adamczewski missed time in 2024 due to injury, but when he was healthy, he performed very well between the Arizona Complex League and Low-A Carolina—as evidenced by his 156 wRC+. He is off to an even better start in 2025.

Adamczewski’s carrying traits are connected to his ability to hit the ball. His hit tool has the chance to be plus, with an ability to hit the ball with some authority to all fields. Chris Clegg of Dynasty Dugout pointed out that Adamczewski made some changes to where his hands are in his load and also improved the base of his stance. Both changes are aimed at improving the consistency of his timing, and helping him lower his ground ball rate from last season. The early returns have been very positive.

While he doesn’t possess huge raw power, Adamczewski’s ability to pull the ball in the air (and to hit the ball at ideal launch angles) does give him a chance to get to more game power than you might expect. He has hit home runs with exit velocities of up to 108 MPH as a teenager, and shows quite a bit of gap-to-gap power, as well, with plenty of doubles and triples on his ledger.

On the defensive side of the ball, Adamczewski’s glovework is certainly solid enough to get the job done, but his lack of arm strength leaves him as a likely second base-only prospect on the infield. He does show strong instincts in the field, and makes the extra effort when possible, especially when it comes to backing up first base. An effort that has been able to net the Mudcats a couple of extra outs in the first month of the season.

No. 15 - RHP Bishop Letson
An 11th-round selection, who was signed away from a Purdue commitment in 2023, Letson had a strong start to his professional career in 2024, posting a 3.13 ERA in his age-19 season. He appears to have made another leap in 2025.

Equipped with a four-pitch mix, Letson throws multiple fastballs, with both a four-seam and a two-seam variation in his repertoire. Both fastballs sit in the 92-95 MPH range, and the four-seamer has touched 98 in the past. That velocity plays up even more, due to the elite 7.5 feet of extension he generates. The two-seamer has around 15-16 inches of arm-side run, while the four-seamer gets a lot of carry. That helps him throw the four-seamer at or above the top of the zone with a lot of success.

Letson’s secondaries are both strong pitches—especially his slider. That pitch is thrown in the low 80s, with quite a bit of sharp movement to the glove side. It’s been a pitch he can land for strikes, but also get a lot of swings and misses with. His changeup is his fourth pitch, showing good fade to his arm side and being thrown in the mid-80s. Consistency will be key for this pitch, as when it’s on, it shows flashes of being another average or better offering.

The biggest jump for Letson in 2025 has come in the form of his improved command. In the early-going, he has essentially chopped his 2024 walk rate of 10.5% in half. If these improvements hold throughout the season (and he shows that he can handle the innings load required), Letson has all the makings of a future big-league starter.

#19 1B Ernesto Martinez Jr
Signed all the way back in May 2017, Martinez is older than your typical ascending prospect, at 25 years old. Despite his advanced age, however, he continues to rise within the organization, and even on the national scale. After a very strong 2024 season in Double-A Biloxi (especially in the second half), Martinez re-signed with the Brewers on a minor-league deal. While he is currently out with an injury, he was off to a great start in Triple-A Nashville.

Standing 6-foot-6 and weighing 250 pounds, Martinez is an impressive athlete. One sign of that athleticism can be seen in his defense at first base. He has the ability to do the splits, and he is happy to show it off. A strong defender over there in general, Martinez should not have any issues holding down the cold corner at the major-league level. Another sign of his athleticism lies in the fact that, while first base is his future position and the spot at which he spends the vast majority of his time, he has also spent some limited time as a center fielder. Martinez even went 20-for-25 in stolen base attempts for Biloxi in 2024. Never mind baseball players; not many human beings his size can move like he can.

While the defense and the athleticism are impressive, the driving factor behind Martinez’s late ascent as a prospect is his offense. His results have been impressive, as evidenced by his 145 wRC+ in Double A, but his process-based numbers have really drawn the attention of analysts. Martinez hits the ball extremely hard, with a 90th percentile exit velocity of 111.5 MPH. For reference, Oneil Cruz leads MLB in that category at 114.7 MPH. Aaron Judge is at just 111.1. Martinez hits the ball as hard as anyone in baseball. 

Most players who hit the ball as hard as he does have issues with whiffs—especially players who have a swing as violent as Martinez’s. Martinez whiffs at a 20.3% rate, though, which would be in the 75th percentile at the big-league level. He also doesn’t chase much. One nitpick would be that he would benefit from being able to get the ball in the air more often, as the home run numbers don’t necessarily line up with the hard-hit metrics. Whether the home run power is there consistently or not, there is a ton to like when it comes to Martinez’s bat.

Martinez will turn 26 in June, and he is showing that he deserves a chance to play in the bigs sooner, rather than later. It could be tough to find room for him this year without an injury to one of the incumbent first basemen on the roster, but Martinez seems to have the inside track (at this moment) for the 2026 starting first base spot. 

What are your thoughts on the three additions to the Brewer Fanatic Top 20 prospects?

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