Now for me, I just don't think the Sox have the deep farm and the players Tampa needs. Jeter Downs is an excellent trade bait and probably a guy the Sox could consider moving for a pitcher, but it won't be Snell (even if they take Kiermaier's contract). Tampa is just too flush with middle infield talent. They might not mind taking another MI but I think they would prefer a catcher, and that tells me the Dodgers (Keibert Ruiz) and the Reds (Tyler Stephenson) are both able to put together more attractive packages to acquire Snell.
I think the Sox need to target Jameson Taillon and sign two from Brad Hand, Hansel Robles and Archie Bradley. (It is possible that only one of them takes an offer from the Sox regardless of money as only one of them can close and all three might have the closer role as a priority. As it is their choice, I can't say that they will all be interested. But so far, this is just mesage board fodder)
Taillon's trade value is actually reasonable on BTV, but it is tough to gauge what player from the Sox they might want. While that site does give Downs more trade value than Taillon, it is not an unreasonable amount for a swap. And as Cherington is a notorious prospect hoarder, he might even be on board with it. Ideally, I would like to see him acquired for someone else, but not sure what Pitt needs beyond players who make little to no money. The Sox most expendable dirt cheap player is Chavis, but even with his BTV trade value actually looking reasonable at 7.5, I just don't see why any team might be interested in him.
Also, the Sox can probably fill the CF void with Ender Inciarte and get him for next to nothing. With the Braves being in the unenviable position of having Inciarte as their highest paid outfielder and not even starting, he should be extremely available from Atlanta.
That just leaves 2B (maybe?) and a LHH bench bat. And the LHH bench bat has always looked like former Bloom acquisition Brad Miller would be the perfect fit for the Sox....