Marcelo Mayer

Mayer will be a big-league regular, but the closer he gets to the majors, the less he looks like a future fantasy star. As one of the slower shortstop prospects of note, Mayer won't be a major threat on the bases, so he has to move the needle at the plate. His walk rate has decreased at every full-season stop, dipping to 7.9 percent in 43 games at Double-A, and his 25.8 percent strikeout rate at Double-A was the worst mark of his career. Mayer reportedly dealt with a left shoulder impingement during his struggles at Double-A, and he eventually got shut down in early-August and received an injection in September. He has a career .280/.371/.494 slash line with 11 home runs in 60 games at High-A, so if the injury was the cause of his issues at Double-A, he could bounce back with similar production to what he showed at High-A in 2022 and 2023. A big reason Mayer ranks highly on real-life prospect rankings is his plus defense at shortstop, and while that figures to guarantee him playing time in the future, that's the extent of its importance for his fantasy value. He could debut late this year, but don't expect him to produce at an acceptable clip in fantasy until at least 2025.

Mayer's top skill so far in pro ball has been his patience at the plate, sporting a career 15.6 BB% in 531 plate appearances from rookie ball through High-A. His strikeout rate has remained a steady 25% while showing average game power as a teenager. Despite middling home run totals, Mayer's 36.0 Hard% and 14.0 Soft% were excellent marks in his full-season debut, and he could end up with above-average or plus game power in a few years. He's nearly physically mature and nowhere near as fast as his 17-for-17 on the bases in 2022 indicates. He doesn't have the typical athleticism associated with shortstop, but most evaluators believe he can stick there, at least early in his big-league career. At this point, Mayer might be more appealing in dynasty leagues for his high floor than his ceiling, but there are still some pretty high-end potential outcomes if he can cut down on the strikeouts in the coming years.

Four of the top six fantasy prospects from the 2021 draft were prep shortstops, and Mayer may be the best of the bunch. Some analysts thought he should have been the pick at 1-1, but he slid to Boston with the fourth-overall pick and signed for slot value ($6.66 million). His bat will be his calling card, as he projects as a plus hitter from the left side who should grow into plus all-fields power. At 6-foot-3, 188 pounds, he has a prototypical frame to grow into without compromising his baseball actions. He is just a fringe-average runner now and should slow down, so his range won't be great, but he's a very smooth defender who makes all the routine plays. Mayer was as good as advertised in his limited pro debut, hitting .275/.377/.440 with three home runs and a 121 wRC+ in 26 games in the Florida Complex League. His patience at the plate was noteworthy (14.0 BB%), and while he didn't face strong competition, he was age-appropriate for the level. His picturesque left-handed swing and extensive track record make him as close to a can't-miss high school prospect as we've seen in recent years.