The Boston Red Sox youth movement continued over the weekend with top infield prospect Marcelo Mayer earning a big-league promotion. With Kristian Campbell already on the roster, No. 1 prospect Roman Anthony will be the last of the "Big Three" to reach the majors.
Anthony's call-up should be imminent. The 21-year-old continues to tear up Triple-A, and his bat would be a welcome addition to a Boston lineup that has been dreadful as of late.
Who are the candidates to take over for Anthony as the organization's top prospect once he reaches the majors? Here's an updated look at how the top 10 players have fared down at the farm this season. (Prospect rankings via SoxProspects.com.)
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1. Roman Anthony, OF
2025 stats: .321/.453/.518, 7 HR, 21 RBI, 42 BB, 43 SO (47 games at Triple-A Worcester)
MLB ETA: 2025
Anthony continues to dominate Triple-A as he awaits a well-deserved promotion to the majors. The 21-year-old has nothing left to prove in Worcester, so he should be called up any day now.
At this point, not even an outfield logjam should keep Boston from adding Anthony to the active roster. The offense has been wildly inconsistent all season and has been virtually non-existent for the last week. Anthony could bring a spark the lineup so desperately needs.
2. Kristian Campbell, 2B/OF
2025 stats: .224/.313/.356, 5 HR, 16 RBI, 23 BB, 53 SO (47 games with Boston)
After an impressive start to his rookie campaign, Campbell has hit a wall. The 22-year-old entered Tuesday hitting a paltry .113 in May with a .315 OPS. This is the first real adversity he has faced since being drafted in 2023 and skyrocketing through the minor-league ranks.
While slumping at the plate, Campbell has taken some practice reps at first base. Now doesn't seem like an ideal time for him to switch positions, especially since he seems to have taken a step forward defensively at second.
If Campbell can't turn it around offensively, Boston may have no choice but to send him back to Worcester to figure things out.
3. Marcelo Mayer, INF
2025 stats: .271/.347/.471, 9 HR, 43 RBI, 20 BB, 38 SO (43 games at Triple-A Worcester)
Mayer earned his much-anticipated call to The Show over the holiday weekend. Nerves seemed to get to the 22-year-old in his MLB debut, as he went 0-for-4 with three strikeouts after losing his car keys in Worcester, but he bounced back with a single and a double in his second game.
Mayer's defensive versatility has already proven useful as he has played three big-league games at third base and two at shortstop. He's also ready and willing to play second base if called upon.
4. Luis Perales, RHP
2025 stats: N/A
MLB ETA: 2027
Perales is still recovering from the Tommy John surgery he underwent last June and will miss the 2025 season. Still, he's the top pitching prospect in the system for good reason. The 22-year-old impressed last season with a high-90s fastball, filthy splitter, and a wipeout slider.
5. Franklin Arias, SS
2025 stats: .353/.407/.461, 2 HR, 26 RBI, 13 BB, 20 SO (19 games at Low-A Salem, 21 games at High-A Greenville)
MLB ETA: 2028
Wondering who will eventually take over for Anthony as the Red Sox' top prospect? Look no further than Franklin Arias.
Arias, 19, has only gotten better since his promotion to High-A Greenville. His advanced bat-to-ball skills and sensational defense at shortstop make him not just one of the most intriguing prospects in the organization, but in all of MLB.
Through 21 games at Greenville, Arias is hitting .360/.406/.517 with two homers and 17 RBI. He'll be at Double-A Portland in no time if he keeps up this pace.
6. Mikey Romero, SS
2025 stats: .256/.329/.474, 5 HR, 18 RBI, 14 BB, 42 SO (34 games at Double-A Portland)
MLB ETA: 2027
Romero has cooled off since his scorching start to 2025 in Portland. The 21-year-old, who was a first-round pick in 2022, has a .670 OPS through 16 games in May.
Despite the mild slump, Romero remains one of the more intriguing hitters in Boston's system. With Mayer now in the big leagues, it may not be long before Romero takes his spot in Worcester.
7. Juan Valera, RHP
2025 stats: 1-2, 5.40 ERA, 1.41 WHIP, 9 BB, 37 SO (Eight starts at High-A Greenville)
MLB ETA: 2028
Valera's early-season numbers don't jump off the page, but the 19-year-old's upside is obvious each time he takes the mound. He boasts a 100 mph fastball and a low-90s changeup that can baffle opposing hitters. His filthy stuff has translated to a 10.0 K/9 through 33.1 innings this year at High-A Greenville.
8. Payton Tolle, LHP
2025 stats: 1-2, 4.13 ERA, 1.20 WHIP, 7 BB, 49 SO (Seven starts at High-A Greenville)
MLB ETA: 2027
Tolle, a 2024 second-round pick, has taken his game to another level this month. In four May starts, the 22-year-old southpaw has amassed a 2.89 ERA with 32 strikeouts and only two walks in 18.2 innings. If he can maintain his elite swing-and-miss stuff, he'll be well on his way to becoming a Top 100 MLB prospect.
9. Connelly Early, LHP
2025 stats: 4-0, 1.55 ERA, 0.97 WHIP, 15 BB, 47 SO (Seven appearances, including four starts at Double-A Portland)
MLB ETA: 2026
Early has been nothing short of exceptional for Portland this season. He hasn't cooled off in May, posting a 0.59 ERA and 0.91 WHIP with a .125 batting average against over three appearances (two starts) this month. A promotion to Triple-A Worcester should be in the 23-year-old's not-so-distant future.
10. Richard Fitts, RHP
2025 stats: 0-2, 3.18 ERA, 1.12 WHIP, 5 BB, 13 SO (Three starts with Boston)
Fitts was reinstated from the injured list Tuesday after missing time with a pectoral strain. The big-league club certainly could use him as the rotation has greatly underperformed after ace Garrett Crochet.