10 MLB Pitching Prospects Who Stood Out In April

Adam Serwinowski, LHP, Reds

Three years into Serwinowski’s professional career, he looks to be an astute signing by the Reds. Drafted in the 15th round in 2022 out of the South Carolina high school ranks and signed for $125,000, Serwinowski is dominating the High-A Midwest League early this spring. Standing 6-foot-5 with a lean and athletic build, Serwinowski repeats his mechanics well and has shown gradual improvements in several aspects in recent seasons.

So far in, 2025 Serwinowski is showing a six-inch increase in his average extension, which now sits at seven feet. This has created a lower release height (5-foot-7) and a flatter vertical approach angle. He is generating 17-18 inches of induced vertical break on average, sitting 93-95 mph and touching 97 at peak. His primary secondary is a low-to-mid-80s horizontal breaking ball that he calls a curveball but is a harder, baby sweeper. He shows solid command of each with the ability to generate whiffs with both pitches. Serwinowski throws a changeup, but it’s rarely used, and his command of the pitch is below-average. He is showing two potentially-plus pitches but will likely need to find a third offering, even if it’s just a bridge pitch to continue to develop as a starter. 

Jose Urbina, RHP, Rays

The Rays seem to always have an interesting pitcher or two lurking in their lower levels each season. In 2025, Urbina fits that description to a tee.

Signed out of Venezuela in January 2023, Urbina made both his stateside and full-season debuts in 2024, and he returned to Low-A Charleston to begin this season. Urbina has made three appearances so far, allowing two earned runs over 11 innings with 13 strikeouts to three walks. It’s a very small sample, but Urbina’s strikeouts are up quite a bit early in 2025. His overall swinging strike rate is up to 13.9%, and it looks like a slight change in his pitch mix has led to greater bat-missing ability. Urbina used a curveball as his primary secondary weapon in prior seasons, but he’s replaced that usage in 2025 with a mid-80s cut-slider that’s seen excellent results. Batters are swinging at his slider 60% of the time and whiffing on more than half of those swings. A high percentage of his whiffs come in-zone, as Urbina has been in the zone with the slider 67% of the time so far.

It’s still around a 50-pitch sample, so it’s reasonable to be skeptical of the sample size. But when paired with mid-90s fastball velocity and two other secondaries, Urbina is taking a large step forward in 2025. 

Jack Wenninger, RHP, Mets

Entering 2025, Wenninger didn’t rank among the Mets Top 30, but he could be pitching his way onto the list now.

Over four starts this season with Double-A Binghamton, Wenninger has dominated. Prior to a difficult start earlier this week, across 20 innings he’d allowed only two earned runs while striking out 32 batters to just five walks. Wenninger enjoyed a solid season in 2024, making 25 appearances across both levels of A-Ball.

In 2025, Wenninger is using a new slider, as he’s ditched the low-80s sweeper of 2024 for a mid-80s gyro slider he shows above-average feel for. So far this season, he is using the new slider more than any other pitch in his arsenal. His fastball velocity is up a couple ticks in 2025, sitting 94-95 mph with above-average ride, while his changeup, which he’s thrown around 30% of the time over the last two seasons, is looking a little more splitter-like. Wenninger has also added a sinker with a distinctly different movement profile from his four-seamer. There are tangible changes in Wenninger’s arsenal to explain his early success. Those changes look sustainable, too, making him a true breakout candidate. 

LeBarron Johnson Jr., RHP, Rockies

Johnson redshirted his freshman year at Texas before three solid seasons with the Longhorns in which he showed swing-and-miss stuff but limited command. Drafted by the Rockies last July in the fifth round, Johnson is off to a strong start to his professional career with Low-A Fresno. Over 20 innings pitched, Johnson has 22 strikeouts to five walks with four earned runs allowed. He’s generating swinging strikes at a rate of 15.4% and ground balls at a rate of 54.3%.

Johnson’s current pitch mix looks different from his 2024 mix. He’s still throwing three pitches—fastball, slider and changeup—but the shape of each has changed. Johnson’s fastball is now more of a cut-ride four-seamer than the previous version, which had more of a traditional four-seam shape. His slider has gone from a cut-slider in the mid 80s to more of a baby sweeper at 85-87 mph. Johnson’s changeup is showing more splitter like shape, as well.

Throwing from a true over-the-top slot, Johnson creates a steep plane of approach to the plate that gives batters an unusual look. As an experienced college pitcher in Low-A, Johnson will have to prove he can maintain this type of success at higher levels to come. 

Bryce Mayer, RHP, Astros

It seems like year the Astros draft a pitcher who will inevitably outperform his draft slot. This year, Mayer might be their top breakout candidate.

Mayer has made four appearances for Low-A Fayetteville, striking out 46.6% of batters while walking 3.4% in 14.1 innings. Carolina League hitters have been overmatched by Mayer’s mix of a four-seam fastball, slider, curveball and changeup. His four-seamer sits 92-94 mph but plays up by generating good ride and run from a low release height due to above-average extension. Mayer has dominated with the fastball early, generating a 34% in-zone miss rate against the pitch.His primary breaking ball is a low-80s slider with ride and heavy sweep. So far, Mayer has shown above-average feel for both the fastball and slider. He throws a curveball around 17% of the time that displays similar sweep to the slider but with significantly more depth. Mayer rarely throws his changeup, which is a clear fourth pitch.

With fastball quality, two good breaking balls and average command, Mayer looks like a breakout candidate. He’ll need to prove it at higher levels, however. 

Michael Carpenter, LHP, Twins

Carpenter was the type of small-school sleeper teams try and sneak through into the later rounds of the draft, and the Twins plucked him out of Madison JC (WI) in the 11th round last year ahead of multiple interested teams.

Carpenter made his professional debut this spring for Low-A Fort Myers and has shown strong stuff. Results have been mixed, as he’s kept runs off the board but has struggled to consistently throw strikes. Carpenter has struck out 10 batters over six innings with a 14.2% swinging strike rate while showing good stuff and mixing three pitches in a four-seam fastball at 92-94 mph, a mid-80s gyro slider and a changeup. It’s been a small sample so far, but Carpenter shows several interesting traits. His command is the biggest question mark, but hopefully that can improve over a larger sample size. There are few lefthanders with Carpenter’s pitch traits and projection, making him a fun sleeper to follow. 

Mason Marriott, RHP, Diamondbacks

Marriott is an undersized righthander the D-backs picked in the sixth round out of Baylor in 2024. He made three successful appearances with Low-A Visalia following the draft last summer and was assigned to High-A Hillsboro to begin 2025. Over four appearances, Marriott has pitched to a 2.29 ERA and 2.32 FIP while striking out 32.8% of batters and generating ground balls at a rate of 55.8%.

Digging into Marriott’s pitch mix, he shows a natural feel for spin with the ability to command his breaking balls with big movement profiles. Marriott’s fastball is a generic-looking four-seamer that sits at 93-95 mph, touches 96 at peak and features below-average vertical break from a higher slot. The pitch is used early in counts to set up his pair of big breaking balls.

His primary secondary is a curveball sitting 80-81 with heavy two-plane break and spin rates in the 2700 rpm range. So far, the pitch has overwhelmed opposing batters, generating a 32% in-zone whiff rate and a 51% chase rate with a high-swing rate. Marriott will also mix in a mid-80s sweeper, but it’s used far less than his two-plane breaking ball. His high-80s changeup is a solid pitch, and he shows the ability to kill lift while generating lots of armside run.

Marriott has great feel for his trio of secondaries and average fastball velocity, but he’ll need to find a better fastball shape to continue to find success as he moves up the ladder of professional baseball. 

Raimon Gomez, RHP, Mets

We covered the flamethrowing Gomez throughout the offseason, first as a potential Rule 5 Draft pick and then again in the rollout of our Mets Top 30 prospects list. After not pitching for most of the last season in the wake of Tommy John surgery in May 2023, Gomez showed a huge velocity jump upon his return in 2025 and is throwing even harder than before the injury.

Over his first seven starts, Gomez is sitting at 99.5 mph while touching 104 mph multiple times. Gomez generates above-average extension and has above-average ride for his release height. His fastball has generated whiffs at a 38% rate so far this year, which will be key to his success going forward. His slider is the only secondary he’s used this season, sitting 89-91 mph with some ride and sweep.

Gomez has the look of a late-inning fire-breathing dragon capable of handling high-leverage duties. 

Joel Hurtardo, RHP, Angels

Signed for $10,000 out of the Dominican Republic as a 21-year-old in 2022, Hurtardo has had an atypical path to professional success. After a pair of mediocre seasons, he ranked as the Angels’ No. 22 prospect entering the season. He was assigned to Double-A Rocket City to begin 2025 and has been good to start the season. Across four starts spanning 21.1 innings, Hurtardo has a 2.53 ERA despite just 13 strikeouts to seven walks.

Taking a look under the hood, Hurtardo has above-average velocity for a starter, as he’s sits at 95-96 mph and touches 98 at peak with two fastballs shapes. He primarily used his two-seam fastball last year but has moved to using the four-seamer as his primary pitch early in 2025. Neither has very good movement traits, as Hurtardo’s four-seam fastball has little ride or armside movement. That means hitting his spots consistently is imperative.

Hurtado’s best pitch is his changeup, which he is using at a higher rate this season and is the only pitch in his arsenal with even average whiff numbers. Hurtardo’s slider is a gyro at 86-88 mph that generates almost no whiffs but is an effective groundball driver.

Overall, Hurtardo appears to be pitching depth for the organization. Unless he finds more velocity or a better fastball shape, he’s unlikely to see a great deal of success in the future. 

Garrett Burhenn, RHP, Tigers

Over three-plus seasons in the Tigers’ system, Burhenn has been a steady, if understated, performer. He had very good seasons in 2022 and 2024 with a 2023 campaign in which the strikeouts disappeared sandwiched in between.

In 2025, Burhenn has made four appearances for Double-A Erie, striking out out 26.8% of batters while walking 7%. The strikeouts and command are backed by a 47.8% groundball rate, as he’s showing multiple pathways to generate outs. Burhenn survives off above-average command and feel for three distinctive shapes that move in different directions. This gives him the ability to move the ball around the zone. His fastball sits 90-92 mph with below-average shape and generic release traits. Burhenn has added some sweep to his slider this season, but it sits in the low 80s with moderate shape. His changeup is an above-average pitch with heavy tumble and fade, and it gets good vertical separation off his fastball.

Burhenn is a pitchability righthander who’s unlikely to add much, if any, fastball velocity in the coming years.