It will be interesting to see how the Red Sox do this year now that they are starting some youngsters up the middle - Jackie Bradley Jr. in cf and Xander Bogaerts @ ss. Bogaerts doesn't worry me as much as Bradley does. I really like the way he plays cf and don't think there will be much of a drop of from Ellsbury defensively, but he's not Ellsbury in the batting order or on the bases.
Third base is another question mark as well, but I think they will make an in-season trade to try and upgrade that postition.
Starting pitching will be fine, would love to see Clay Buchholz play whole season and not have a teacher's summer schedule (DL mid-late June and comeback in September).
Bullpen should be fine as well, just hope that Koji Uehara can turn in another fine perfomance he did last year, otherwise it's closer by committee.
Gonna be a great season for sure, the American League East has some good quality respectable teams this year.