The Boston Red Sox have been trying to thread the needle between winning now and developing superstar prospects, and it's created sticky situations galore. Second baseman Kristian Campbell joined the team straight out of spring training and signed an eight-year extension shortly thereafter.

Mayer, who hits seventh for the Red Sox, gave Boston the lead in the second inning Wednesday. With the game tied 1-1, Mayer launched a first-pitch slider from Rays starter Zack Littell over the right-field wall at Fenway Park.

Welcome to this week's RotoBaller Rookie Report for Week 12 of the 2025 season your spot for keeping up with MLB's rising stars. In this edition, we're checking in on three young players who've just hit the big leagues or are still rocking that rookie tag as the season rolls on.