Marcelo Mayer

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.