It certainly appears that the defense is getting the overall best of it against the number 1 offense in the league.
I read somewhere that Peyton Manning was getting on the D at some early point in 11 on 11s - to mount a better pass rush - that they were not going full speed. I think that Peyton Manning the way he is - has made sure - that he can practice against the mad rush physical defense -and that's what he is getting for the most part.
One thing that happened to the Bronco offense in the alleged Super Bowl was its timing was disrupted - either on the receivers going down field, or on the Manning having less time to release the ball. What better way to defeat that tactic than to practice against it? Good on Peyton Manning for demanding it.