Honestly? Deny. There were far more over-rated games this gen like, idk, Skyrim?
I'm not going to deny that MGS4 is certainly flawed or weaker in certain areas but at least a majority of fans will acknowledge these imperfections when presented in a non-exaggerated, respectable format.
Skyrim? Filthy casuals are going to be hailing that game as the best game ever for a few more years. To a majority of them, it's perfect.