Even their lead director is a moron. His philosophy apparently is "Well it runs at 60fps and that is what you guys want, we can still make the engine pretty"
The reality is they've only ever worked with someone elses engine and can't f'ing design their own. And even the COD fanboys are starting to notice nothing ever changes. Same textures, same death animations, rehashes of old maps, recycled sounds. It's no wonder they make so much profit on the damn games they barely change a damn thing.
The fact that almost a decade or however long it's been since the first COD, that they're still using a modified version of Quake3 Arena ffs speaks volumes.