Another thing was that the Ravens changed their coverage up. Manning mentioned this in his press conference. In the 2nd half they switched and went to a lot of 2 deep safeties and just had Pollard and Reed playing deep safety. They weren't going to let him go deep. You could see it too because they didn't blitz as much. I'm amazed it took the Ravens that long to figure it out.
That's what beats Manning... that's why Crennel usually did so well. You can't attack him, you gotta sit back and let him go into robot mode and dink and dunk and check off to runs. They only team that seems to be able to attack him and do it well is the Chargers.