To be fair, if Lester goes back to an 18 win, 3.50 era pitcher and Buch goes back to a 15-17 win, 3.70 era pitcher, which is what 'bouncing back' would be to me, then this team is an absolute contender.
Toss in a stupid good bullpen, assuming they add Hanrahan, very good SP depth via prospects, not retreads in AAA (Webster, Workman, De La Rosa), and you've got a contender.
Regardless of what the Sox did this offseason, this team goes no where without Lester and Buch being the pitchers they can be. They don't need career years. Just a solid year, back of the baseball card.