Analyst Michael Olson, of PiperJaffray, has pointed the finger for low retail revenues at the Call Of Duty series' falling lifetime sales.
While no-one can dispute the success of the series, he argued the games aren't selling as many or for as long as previous iterations.
"We believe big name titles are no longer able to sustain 'fat tails.'" he told Gamasutra.
"This 'thinning tail' phenomenon is driven by 1) casual gamers leaving the market, 2) a steeper pre-sale and up-front curve, and 3) cannibalisation from the pre-owned market."
He pointed out that the latest Call Of Duty title, Modern Warfare 3, will probably sell less than half of Black Ops total, and coming in as the eighth largest selling game in March 2012, as opposed to Black Ops fifth place spot last year.
He also predicted a 26 per cent drop in software sales when NPD Group results are published later today.