According to their numbers, by March the number of copies of MW3 sold was 4.2% behind where the first Black Ops title had been at the same time a year earlier.
Nearly all were multi-platform across PC, Xbox and PS3, but none but MW3 were released for the Wii, and no one is going to argue that version was superior to the others.
But if DICE and EA can manage even to put a dent in MW3 sales, Activision will take notice, and perhaps put a bit of extra effort into their golden goose the next time around.