I still see the AL East as a close three-team race. A lot will depend on injuries.
(1) Boston's line-up is overwhelmingly left-handed. While this is not generally a problem (most pitchers are right-handed), the AL East is home to some of the better lefties in the AL: Cash Cow, Price, Romero, Cecil, and Matusz. Also, it makes the Sox susceptible to left-handed relief match-ups in big spots.
(2) The rotation. This has been mentioned before, but a lot will depend on how well Beckett and Lackey bounce back. Lester is legit and I don't see Dice-K as a problem. While Buchholz is good, I don't expect his results to be as good as they were in 2010. If all goes well, the Sox could have one of the top rotations in baseball. Even if Beckett and Lackey struggle, Boston's rotation should still be good--but maybe not as good as the other AL contenders' rotations.
(3) The bullpen. They look good on paper. But bullpens are tough to predict. How good are Paps, Jenks, and Wheeler? Wheeler is a pretty extreme fly ball pitcher. How well will he do at Fenway? Jenks had good secondary numbers last year. He was hurt by BABIP, which could be bad luck (although his LD rate was up). As for Paps, who knows? Dannys Reyes is a LOOGY. However, his numbers against lefties last year weren't great (5.21 BB/9 v. left-handed hitters). Albers is nothing special.
The Sox do appear to have bullpen depth in the minors, though. Atchison, Aceves, and Doubront are decent pitchers.
(4) Catcher. Jarrod Saltalamacchia/Jason Varitek. 'Nuff said. If Salty can play average defense and OPS around .750, the Sox will be OK at the position. He's no lock to do either. His career OPS is .701.
(5) Defense. Drew, Crawford, and Pedroia (assuming no loss of range due to last year's injury) are good defenders. Gonzalez is good, but not as good as Youk, at 1B. Youk isn't likely to be as good as Beltre was at 3B last year. Scutaro is average at best at short. So far in his career, Ellsbury is a better corner OF defender. Salty has been solidly below average at catcher. There's a chance that the Sox may be below-average defensively at three premium positions: C, SS, and CF. I'd really rather see Lowrie start at SS. He has much more upside than Scutaro, and I don't see him getting more than 250 AB as a "super sub" (assuming everyone is healthy).
Overall, if healthy, the Sox should be a lock for 95-97 wins. Last year's team was decimated by injuries, had a historically bad bullpen, a poor defense, and still won 89 games, despite a struggling Beckett and Lackey. While I don't see this year's team as being that much better than last year's team on paper (except in the pen and bench--Cameron, McDonald, Lowrie, and Tek are a great bench), the Sox would have won the division if they hadn't lost so many good players to injuries. So if they're healthy this year, I expect them to win the East.