Kim is potentially an elite pitcher--and we all know how rare those are. Hillenbrand is a nice player. Mueller will fill in nicely--not much power, but a good player with good OBP and Boston has other players to take up the slack.
So, as far as upside, the deal is best for Boston.
As far as short-term, Kim may be the missing piece to finally put Boston over the top--long term he's probably a starter, but he can kick their bullpen in the keyster this year, which is what it needs.
Dave N