User blog comment:Damac1214/Sales of Black Ops II are a "Cause of Concern" for Activision/@comment-98.230.84.179-20121202021551/@comment-98.230.84.179-20121202045420

But they are still released yearly. Also, 2 years isn't that long when it comes to developing games. Considering that they need a solid build of the game by E3, that means they have an alpha version up made within 8 months. To do that, they have to heavily borrow from past titles rather than design new things.