Getty Boston Red Sox prospect Marcelo Mayer Although he has become a top-10 prospect as a shortstop, many MLB analysts believe Marcelo Mayer will make his Major League debut with the Boston Red Sox at first base.   But Joel Reuter of Bleacher Report sees Mayer’s future unfolding across the diamond as MLB’s top player at third base.   Red Sox fans have been eagerly awaiting the arrival of Mayer at Fenway Park since he was drafted as the No. 4 overall pick in the 2021 draft. One of “the Big Three”