This article, from the guy at football outsiders, illustrates just how lucky Denver has been this year. They could easily be 0-6 and the line for this game would be completely different.
http://sports.espn.go.com/nfl/news/story?id=3080360
Not stated in the article, but along the same lines - Denver's pythagorean win % (using exponent of 2.37) is .262 so far this year.