Yeah, it's a tricky time to market a big AAA title at the moment. Trying to compete with the titans of Battlefield and Call of Duty is difficult a the best of times, let alone when the latest instalments of both have just been released. And given the lacklustre reception of the first due to the lack of single player campaign and the "get boring rather quick" multiplayer I can see why they think it won't sell.
They kinda have to get it out now, ready for the Xmas rush though. Leave it too late and you don't give the parents enough time to get it for lil Bobby, release it early and you're competing with every other Christmas release. Damned if you, damned if you don't.