I think folks haven't really been paying attention to Green Bay this year. They got a lot of national attention early on, particularly during the Seattle game, but as we've seen, that Seattle team isn't the same as in the last couple of years. The Packers have only played two games on the road to this point, at San Fran and at Chicago, who are both awful. Their win against St. Louis was a good one, but aside from that, they haven't really looked like the best team in the NFC lately.
It's not all their doing though. The loss of Jordy Nelson stings, a lot, and Lacy, Cobb, James Jones have all been playing/not playing through injuries for most of the season. I think this is a case of them finally being exposed a bit by a good defense.
On the other side, things just seem to be falling really well, schedule wise, for Denver. They've had opponents hand them games all season long. They haven't really played anyone who was good on both sides of the ball until tonight, and of course, they catch Green Bay at home, while GB is playing some of it's worst ball of the year. It's no surprise they also get New England at home. Denver is going to win 14, minimum.