Whit Merrifield, 2B/OF
As far as position players go, it would seem Boston's biggest target could be Juan Soto. But as that would require a trade with the San Diego Padres, we obviously can't include the three-time All-Star here.
Whit Merrifield may not be available in free agency either, as there's a mutual option on his 2024 contract with Toronto. However, that option is worth $18 million, and there's a strong chance that the Blue Jays will decline their side with the hope he'll return at a reduced rate.
If Toronto declines, don't be surprised to see the three-time All-Star test the market, especially given the solid season he just had in helping the Blue Jays to the postseason. In 145 games in 2023, Merrifield hit .272 with 27 doubles, 11 home runs, and 67 RBI, adding 26 stolen bases.
Since making his big-league debut in 2016, the South Carolina native has slashed .284/.330/.420 and has made at least 550 plate appearances every season except 2020. So he's another reliable and durable player. He's also versatile in the field as he can slide in at second base, where the Red Sox have had problems, or play all three outfield spots when necessary.
Is Merrifield the most high-profile (possible) free agent out there? Of course not. But he's the type of guy you want on your team when attempting to make a run at a World Series.