I also don't really see where he'd fit in. Beni-JBJ-Mookie with JD at DH is already solid. Unless Sox would deal Beni in this type of deal, which Id be completely against.
Things to keep in mind with Renfroe - His fielding is bad, he is essentially a one trick pony - power. He doesn't get on base or hit for average. Career .299 OBP is concerning. I think he's good, but will demand more than he should. Overall, I don't think Sox are a match for him, he's not the guy I'd want to overpay for.