#4 - Shohei Ohtani - DH
Now we are talking. The Red Sox have been one of several teams connected with the elephant in the room that is Shohei Ohtani's free agency. The roster fit in Boston for a guy that can only DH next season isn't perfect, but Ohtani is such a unique and special player that Boston should happily try to figure it out assuming they can actually sign Shohei.
Ignoring Ohtani's ability on the mound when healthy for a moment, he was a monster at the plate in 2023 for the Angels. Shohei put up a staggering 1.066 OPS in almost 600 plate appearances with 44 home runs and 20 stolen bases. If he hadn't gotten hurt, it is highly likely that he would have easily eclipsed 50 homers and put together one of the best offensive seasons the sport of baseball has ever seen.
Shohei's elbow injury and subsequent surgery does matter here, though, and is one reason why he would only be batting fourth here to start with. The initial word is that he will be able to hit from Opening Day on, but a certain amount of caution from the outset seems to be wise including giving him some days off here and there.
Again, a lefty power bat that needs to DH isn't exactly the perfect fit for a team that has Yoshida, Triston Casas, and potentially Soler. However, there is also the long-term plan to think about and Ohtani's contributions as a pitcher can't be ignored. Assuming his rehab goes well, Boston would be getting a top flight starter for 2025 and beyond in addition to bolstering their lineup in one (very expensive) player.