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Lauren analyzes top fantasy baseball prospects risers, fallers, sleepers and busts for 2025. Her MLB rookies report for Week 7 and recently promoted prospects.
Welcome back to another edition of RotoBaller’s rookie report, where we track the rising and falling stock of top MLB prospects. This week, we’re spotlighting three rookies — some recently promoted, others still holding rookie eligibility heading into the 2025 season.
In our last report, we covered Jackson Jobe, Rhett Lowder, and Nick Kurtz, each navigating the ups and downs of their debut, while offering glimpses of their high-end potential.
This time, we turn our attention to Coby Mayo, Kumar Rocker, and Blade Tidwell. Let’s take a closer look at their profiles and what lies ahead with their big-league clubs.
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Coby Mayo, 1B/3B, Baltimore Orioles
Orioles' No. 2 and MLB's No. 11 prospect Coby Mayo recently received a second chance in the big leagues after a 17-game stint with Baltimore in 2024. The O's can use any reinforcements they can get, as they sit in the basement of the American League East with a 13-23 record, 7.5 games back of the first-place New York Yankees. Unfortunately, Mayo hasn't given them the spark they've been searching for thus far.
Track Record:
The Orioles drafted Mayo out of high school in the fourth round in the COVID-19-shortened 2020 MLB Draft, along with fellow former top prospects Jordan Westburg and Heston Kjerstad. All three have made their MLB debuts, but only Westburg and Kjerstad have been able to stick with the major league club. Mayo debuted in August 2024, collecting just four hits, four walks, and striking out 22 times across 46 plate appearances.
He didn't inspire much confidence during spring training this year, either, so he began the year with Triple-A. Mayo produced an .869 OPS with 15 extra-base hits in 28 games. For his minor league career, the 23-year-old has slashed .281/.378/.539 with 88 home runs, 304 RBI, 220 walks, and 431 strikeouts. Mayo doesn't have much left to prove there, but he's left a lot to be desired at the MLB level.
Outlook:
Since re-joining the O's on May 3, Mayo has appeared in four games, logging a hit, a walk, and six Ks. His propensity to strike out is a problem, but he's only played in 21 games at the big league level. Mayo likely needs additional reps to reduce his strikeout rate, as he managed to do in the minors, cutting his strikeouts from 148 in 2023 to 102 in 2024.
Coby Mayo with his first hit of the season on a low and away slider (and with an EV of 109.3 mph, to boot): pic.twitter.com/e1SiW8zEQC
— Avi Miller (@AviMiIIer) May 8, 2025
Mayo has drawn comparisons to Atlanta Braves third baseman Austin Riley, with evaluators citing his size (6-foot-4, 230 pounds), power, and bat speed as similarities. The youngster must start small, working on his plate discipline to draw more walks, and then begin to utilize his power to drive the ball over the fence.
Kumar Rocker, SP, Texas Rangers
Few top prospects have had as much of a rollercoaster path to the majors as Rocker has. The former Vanderbilt standout was initially drafted by the Colorado Rockies in 2018, but declined to sign, being committed already to the Commodores.
He accumulated numerous accolades there, including Most Outstanding Player of the College World Series as a freshman in 2019, and threw a 19-strikeout no-hitter vs. Duke. His college career once again put him on the radar of MLB teams, and the Mets selected him 10th overall in 2021, but the team retracted its offer after a failed physical.
Track Record:
Rocker then played in the Arizona Fall League and Independent ball in 2022 before being redrafted, this time by the Texas Rangers, with the third pick in the 2022 draft. While many injuries have set him back, Rocker has remained resilient. He pitched across three levels in the minors in 2024, posting a 1.96 ERA and 55 strikeouts across 36.2 innings in 10 starts.
The 25-year-old right-hander made his long-awaited MLB debut on September 12, 2024, fanning seven Mariners in four innings. Overall, in three starts for the Rangers, he recorded 14 Ks in 11.2 innings. Rocker had a short leash, with his longest outing at 4.2 innings vs. the Athletics. The Rangers decided to enter the 2025 campaign with Rocker in the rotation. In five starts, he's yielded mixed results.
Career-high eight strikeouts for Kumar Rocker 🔥
Dialed in. pic.twitter.com/pVKn5hBlfA
— Victory+ (@victoryplustv) April 18, 2025
Outlook:
Rocker's 2025 debut saw him allow six runs on seven hits in three innings against the Cincinnati Reds. His following four starts weren't much better, outside of a seven-inning showing vs. the Los Angeles Angels on April 17, where he struck out eight, walked none, and allowed three runs on five hits.
Rocker possesses an 8.10 ERA and 1.75 WHIP across five starts, and his underlying numbers aren't much better. His low BB% and groundball rate barely kept him afloat before he was placed on the injured list with a right shoulder impingement on April 24.
When Rocker returns, taking control of his fastball command will be paramount, as hitters are currently hitting .455 against it. Refining his arsenal, primarily his breaking stuff, will also be key to Rocker's future success. He's all over the place with a curveball, slider, change-up, and even the occasional cutter finding its way into the mix.
His slider is his signature pitch, but he must fine-tune another breaking pitch to be effective at the big league level. Perhaps another stint in the minors will help him get right.
Blade Tidwell, SP, New York Mets
With the amount of injuries to the Mets' rotation, including Frankie Montas and Sean Manaea, New York has had to employ several pitchers for spot starts. The Mets selected the contract of their No. 15 prospect, Tidwell, on May 4 to start against the St. Louis Cardinals. It didn't go well.
Track Record:
Tidwell was selected in the second round (52nd overall) of the 2022 MLB Draft. In his first full season in the minor leagues in 2023, he impressed with his strikeout numbers, fanning 153 batters in 116 innings pitched between High-A and Double-A.
Tidwell started the 2024 campaign in Double-A with a 2.41 ERA, paving the way for his promotion to Triple-A. That is where his struggles began. He has a career 5.71 ERA in 25 games (23 starts) at that level, along with 63 walks and 114 Ks across 112 frames of work.
Unsurprisingly, Tidwell didn't fare much better in his big league debut, surrendering six runs on nine hits in just 3.2 innings, striking out two and walking three. He was optioned to Triple-A the following day.
Outlook:
So, where does Tidwell go from here? Can he right the ship, or is he cooked? The simple answer is no. The 23-year-old still possesses a strong arsenal, consisting of a fastball that tops out at 98 mph, a slider, sweeper, and cutter. The sweeper was particularly effective against righties.
According to MLB.com, some evaluators "believe Tidwell may have been getting too fine in his location and that he needs to trust his stuff will play in zone more often." If he's unable to do so, it's possible Tidwell's stuff would translate better in a relief role moving forward.
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