Your defense did make the stops.
You gave up 4 turnovers and we only got, was it like 10 points off it? 13?
Peyton lost that game by playing like shit in the 1st quarter and throwing 3 INT.
They needed one more stop to get the ball back at the end of the game. IRC Jones caught a pass to convert the first, when Rahim Moore didn't come up to meet him and make the tackle prior to the first down marker.
They did make stops earlier in the game, but that one critical stop didn't happen. Yes, Peyton played bad and dug the hole, but he also helped dig it out.
I'm not arguing that they didn't make the stops during that game, they just didn't get the one where they needed it to get the ball back.
In the Houston game, they seemed to be worried about Foster and didn't respect Schaub and got burned deep. They came back again, and missed a critical stop again when Johnson caught a pass to convert the first, right pass the outstretched arms of Champ. Denver ran out of time again with that conversion.
Get either one of those stops and hypothetically they are different games. It didn't happen, but they were one stop and a TD drive from winning both.