There's a lot of depth at both OF and pitching in the minor leagues. I feel like that could be used to get a good return either this year, or next. Nava looks major-league ready, and it seems Kalish/Reddick/Westmoreland (if he's able to return to baseball) are all highly rated, though Reddick has not impressed this year. Similarly, Doubront is close to ML ready, and Bowden has the chance to impress, but I'm not too optimistic there. That, however, seems like a lot of pieces for positions where the Sox are respectively decently off (Ellsbury looks good, Nava is IMO ready to compete for a starting job, and Drew's spot will be opening up right as the Kalish/Reddick/Westmoreland trio mature), and getting suffocated by depth (Lester, Beckett, Buchholz, Lackey, Dice-K).
I feel like that's a lot of tradeable assets (more if you include Buchholz and Bard, but I think they're untradeable now), and giving up a package of 2-3 of those players along with potentially a player further out for a power hitter is both viable and necessary, given the glut of starting talent.