There isn't an injury that makes you stare down receivers and throw it into triple coverage.
There is if you have no desire to move because it hurts too much to do so. If you don't want to move you basically have to stare down a receiver and hope he gets open.
I'm not making excuses for Manning as he was beyond awful, but if he is truly injured as it appears, then this falls on Kubiak for letting him go into the game.
And for that matter I'm going to be pretty upset if Manning is starting next week against the Bears. The guy is clearly not right, anyone with a brain can see that. Let Brock play, that's why you have a backup QB, in case the starter isn't right. The 2nd super bowl year Bubby Brister started 4 games for an injured John Elway. The team just has to step up around the backup. Let Brock play against the Bears, and let Manning rest. Hell I'd even start Brock against the Pats, it's not like we are going to catch them for home field advantage. Get Manning right so he can at least be healthy for the playoffs. And yes we are going to make the playoffs, we are going to win at least 3 more games the rest of the year, and 10 will get you in.