Gamasutra did a good comparison about BLOPS 2.

That a 16% and 7% drop over MW3 and BLOPS 1 respectively.
But they did a estimation for more 7 days in the market putting BLOPS 2 at 7.9m almost matching the BLOPS 1 numbers... 10% down compared to MW3 through.
http://www.gamasutra.com/view/news/183066/Numbers_show_The_Call_of_Duty_decline_looks_real.php







