13 Breakout MLB Prospects For 2021 Season

Image credit: Gunnar Henderson (Photo by Tom DiPace)

Any Top 100 Prospects list is a snapshot of a moment. What Baseball America knows now will change next month, as players start to arrive to spring training. And once minor league games resume in earnest (hopefully) later in the spring, there will be a lot more data, scouting reports and other information to assemble and process. With that in mind, here are some prospects who could massively improve their standing within the Top 100 in 2021, as well as some prospects who could move into the Top 100.

Inside The 100, May Move Up

Quinn Priester, RHP, Pirates

Sure, prep righthanders taken in the first round are risky. But every now and then teams do pick a Mike Soroka, Ian Anderson or Jack Flaherty. And Priester has many of the attributes one looks for in a successful prep first-round pitcher. He’s come into more velocity as his teens turned to his 20s. He’s already shown he can locate his breaking ball and his delivery is clean and in sync. With a full season to show what he can do, Priester could rank much higher on the 2022 Top 100. (JJ Cooper)

Noelvi Marte, SS, Mariners

If Marte were in any other organization, he would have already had his U.S. debut in the Rookie-level Gulf Coast League or Arizona League, but the Mariners are ultra conservative when it comes to keeping their Latin American signings in the Dominican Summer League for their first season. Marte crushed the DSL. No surprise there, as he was one of the elite international prospects in the 2018 class and not far off Giants shortstop Marco Luciano at the time. He keeps trending up, as a power/speed threat with a well-sequenced swing that plays in games. Once he starts to perform against full-season pitchers, Marte has a chance to skyrocket up this list. (Ben Badler)

Robert Hassell, OF, Padres

Hassell checks all the boxes you want to see from a prep hitter. He has been the best hitter for his age at every level since he was 13 years old in the 2014 Little League World Series, and he continued to show the traits of a special young hitter during instructional league in the fall. Hassell has elite strike-zone discipline, drives the ball from line to line, has shown the ability to barrel the ball even when he’s fooled or off-balance and made rapid adjustments against older pitchers throughout his time at the alternate training site and in instructional league. As a bonus, he shined in center field defensively with light feet, quick reads and reactions, a good first step in every direction, a strong, accurate arm and a keen awareness for the game and different situations. Hassell’s eventual power output is up for debate, but hit-first, power-later is the way to go with prep hitters. It should not surprise anyone if Hassell goes out and lays waste to opposing pitchers next year in his first full season of pro ball, and he will jump up the Top 100 if he does. (Kyle Glaser)

Outside of the 100, May Move In 

Gunnar Henderson, SS, Orioles

Drafted with the first pick of the second round in 2019, Henderson made his pro debut in the Rookie-level Gulf Coast League that summer. He finished strong in the GCL and carried that momentum into 2020—though it was largely invisible because it occurred at Baltimore’s alternate training site and instructional league. The 19-year-old lefthanded hitter showed plus raw power and the barrel control to be an overall offensive threat.  (Matt Eddy)

Cade Cavalli, RHP, Nationals

Cavalli combines a powerful arsenal with a prototype starter’s build and athletic delivery. He pitches in the mid 90s and bumps 98 mph with a true power curveball that has developed more true, 12-to-6 action since he turned pro. He continues to show good feel for a changeup. The Nationals drafted Cavalli 22nd overall out of Oklahoma in 2020, and the 6-foot-4 righthander looks like a steal at this point. A big season in 2021 will put him squarely among the Top 100 Prospects. (ME)

Pete Crow-Armstrong, OF, Mets

The first thing people tend to point to with the Mets’ 2020 first-round pick is his defense. There’s strong consensus on that aspect of Crow-Armstrong’s game. He has the athleticism, speed, instincts, range and arm to be a plus defender in center field. As much as Crow-Armstrong’s defense is impressive, what also stands out is his hitting ability. He has a fairly simple lefty stroke, good contact skills with the ability to square up fastballs and offspeed stuff to all fields and a good plan at the plate for his age. There was a gap in the draft between where he was selected (19th overall) and the three other big high school outfielders—Robert Hassell (8th), Zac Veen (9th) and Austin Hendrick (12th)—but he belongs in the same tier as that trio. (BB)

Luis Medina, RHP, Yankees

In a system packed with talented righthanders, Medina’s pure stuff stands alone. Until the end of 2019, however, his pitches had been negated by well below-average control and command. Per nine innings over the course of his career, Medina has struck out 10.7 hitters and walked 7.1. Once the Yankees changed the way Medina pitched, his natural talent showed up more often.  

Over his final four starts in 2019, he allowed 11 hits and six walks over 22.2 innings split between Low-A and High-A. He struck out 31 in that span. After a summer at the Yankees’ alternate training site in Scranton/Wilkes-Barre, Medina went to the Puerto Rican Winter League. He struck out 32 in 16.2 innings there and won the league’s Pitcher of the Year award. (Josh Norris)

Reid Detmers, LHP, Angels

Detmers’ stuff doesn’t jump off the page, but he knows how to pitch and commands the ball to all quadrants of the strike zone. Detmers landed just outside the Top 100 entering the 2021 season, but should easily find his way onto the list if he pitches the way his stuff and poise allows. (JN)


Casey Martin, SS, Phillies

It’s easy to fall in love with tooled-up players, and Martin was one of the best in this year’s draft class. There are legitimate questions about his ability to hit, but if pro coaches can coax even a fringe-average hit tool out of him, he could be a steal in the third round. Martin already has potential plusses with his arm, defense, raw power and speed, which gives him a huge upside once he makes his official professional debut. (JN)

Alexander Mojica, 3B, Pirates

Even while playing most of the season at just 16 years old, Mojica had a tremendous professional debut in the Dominican Summer League. He posted a league-leading 1.048 OPS, including eight home runs and 14 doubles. There are questions about whether he can stay in good enough shape to stick at third base, but the early reviews on his bat were very positive. (JN)

George Kirby, RHP, Mariners

In his pro debut, Kirby lived up to his billing as a supreme control artist. The righthander, whom Seattle chose with its first-round pick in 2019, struck out 25 and walked nobody in 23 innings at short-season Everett. His stuff has ticked up since then, with his fastball touching 99 mph at the Mariners’ alternate training site. If he can continue to carve the strike zone with an improved arsenal, he could move quickly into the upper realms of the game’s best pitching prospects. (JN)

Rece Hinds, 3B, Reds

On the basis of eight professional at-bats and a .000/.200/.000 slash line, Hinds has not yet had a chance to show what he can do in an official minor league game. A quad injury wiped away almost his entire 2019 pro debut, and the lost 2020 season meant he spent the end of the summer facing more experienced pitchers at the alternate site instead. He should have been carved up by pitchers who were in many cases MLB ready, but after a slow start, he started to show the power that made him one of the best sluggers in the 2019 draft. A chance to face more age-appropriate pitching in instructional league allowed him to thrive. He slugged over .700 there, while posting top-of-the-scale exit velocities. Hinds has shown improved pitch recognition and doesn’t chase as many sliders off the plate as he did in high school. If he can continue to improve his pitch recognition, his massive power could help him crack the Top 100 by the end of 2021. (JC)

Bobby Miller, RHP, Dodgers

The shortened college season presented a unique opportunity for teams picking at the back of the first round. Many players who might have played themselves into the middle or top half of the round with a full season didn’t get a chance, providing teams access to a higher caliber of players than are normally available at picks 25-30. Miller was one of those fast risers on his way to pitching himself into the top half of the first round before the season shut down. He showed he could start, made huge strides with his control and showed flashes of being an overpowering force. Those strides continued after the Dodgers snagged him 29th overall. He improved his delivery to be more compact, got more on line to the plate, was able to land his breaking balls where he wanted both in and out of the zone, showed an above-average changeup and averaged 95 mph on his fastball while showing an aggressive, take-no-prisoners mentality on the mound.

If that sounds like a potential front-of-the-rotation starter, that’s because it is. Evaluators overwhelmingly considered Miller a No. 3 starter at worst based on what he showed at instructional league, with most noting that was a conservative projection. If Miller goes out and carries that performance into 2021, it won’t be long before he is not only in the Top 100, but one of the top pitching prospects in baseball. The Dodgers have made a killing on draft picks in the back half of the first round in recent years—see: Corey Seager, Walker Buehler and Will Smith—and Miller may be next in line.  (KG)

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