He didn't come across well with his comments about how he was happy going to the Bruins because he wouldn't be the "focal point" of the team there (because they already have Pasta, Bergeron, Marchand) and he wasn't comfortable being the guy on a team every focuses their attention on.Hall will play well for the rest of this season, get the big contract from Boston (or someone), and eventually get lazy and disinterested again.
There are probably plenty of good teams he could have signed with last offseason if he let the market know he was willing to sign for a second line winger salary. I suspect he still wants to get paid like a star even though he wants none of the responsibility that goes with that.