First off, let me reiterate the comment "one of those guys" to which you specifically seem to defend the ideal of trading Rafaela "ok so trade Duran then" lol.
It's not like what I'm saying is far fetched, it has been suggested and predicted by just about every single pundit out there that the Sox will trade from their outfield depth.
Right now, I'd say it would make more sense to trade from your surplus to plug up a hole E.G. 3B or 2B. but if they went out and signed one of those guys a trade still makes sense for assets. You have a clear defined spot for Yoshida on your roster who isn't prototypical or elite but he is a good hitter at DH.
I also disagree that keeping farm assets and restocking the farm isn't in the best interest of being in a "championship window"
Teams in championship windows trade for elite assets at the deadline, something you won't be able to do with a depleted farm and would certainly have an easier time doing over your competition with a deeper farm.
What if Crochet goes down, or Anthony, or Story or whoever? It's not like high end prospects are just trophy's you put on the wall to show your friend how cool your prospects are. They're used to trade for MLB pieces and provide depth when guys get hurt.