You don't need a quote man, it is their business to know when all their competitor titles are being released. There is no possible way that they did not know there would be another COD in November 2011.
They chose 11.11.11 very carefully
... yeah, very carefully.. "hey, palindromic date acoming... 11.1.11 is already taken, bummer... hey! 11.11.11! Brilliant!"
Bottom line, it will affect sales.
The hard core fan of either game will stick to his/her favorite game.
The casual video game players, however, are finicky, and these are the great majority of buyers. And speaking of Christmas, the gift buyer is even more finicky: unless they know the preferred genre of the person for which they are buying the gift, they probably choose a game for how cool the cover of the game is, and at least in the US, dude with guns will always be more attractive than dragon/dude with sword.