User blog comment:Damac1214/Treyarch hints at Black Ops II Multiplayer trailer/@comment-80.180.83.79-20120726075840/@comment-1263839-20120728184708

Two maps, they released 7 maps in Black Ops (3 at release)... and the hype for Zombies was increased in Black Ops, and Treyarch fed off it, neglected multiplayer and poured all their effort into Zombies after the even bigger rise in it's popularity.