I hate it when they do this. I remember Big Red One on the original Xbox. It was a console-only COD game and it looked like SHIT. It was built for the Playstation 2 and ran horribly.
The Xbox should have HANDLED this game but it ran horribly. The framerate was locked I believe so that it ran identically to the PS2 version.
This is beyond doubt as COD 3 came out at some point and looked FANTASTIC and ran great!