I'm not a hockey fan, so I'll take the Bruins out.
I went for the Pats, mostly because I think they have a smaller window. Brady is getting older, as is Moss. I'm also still bitter about the Giants loss.
With the Sox, the fact of the matter is that this is the planned "down year" and while they're currently in 4th place, they're surging and still have a record that would put them in first in most other divisions. Knowing that they're going to have more money to spend this summer and the fact that they have a bunch of great prospects coming up makes winning another title more a matter of time than an uncertainty.
With the Pats, it's a little different. There may not be too many more shots.