QB>RB.
CJ2K just had a freaking 2000 season, and didn't won the award. Enough said.
It's a joke to think otherwise. It's 70% sure the best QB with the best team will win MPV. And if said QB has a brilliant season, doesn't need to be 50TDs season, he'll win it 99% of the time, even if a RB has a monstruous season.
It's the way the NFL is today. Noone would've thought 10 years ago that there would be 5 QBs with a 100+ rating... It just happened.
PS.: and, of course, if a QB doesn't have much better numbers than Manning, Manning wins. It's the rule.