You can't answer the question now because who knows what the team is going to look like in 4 months. If the Yankees trade AROD to the angels for ervin santana, one of their young 3B, and a prospect and don't sign one of matsuzaka, zito, and schmidt, and the REd Sox do sign one of those guys i'd put the Red Sox as favorites in the east.
If no big trades are made the Red Sox season is going to heavily depend on Coco Crisp, Josh Beckett, and Jason Varitek having years more like they had 2 years ago as well as some development from Papelbon in the starting rotation, youkilis, MDC, and Hansen.
The Red Sox might win more games than anyone in baseball next year and they might finish 3rd in the East, its way too soon to tell. As for the central teams, Cleveland also has a chance to be better than the Red Sox but those 4 teams in that division are all good and all play each other alot. It should be a very interesting division next year.