The Seahawks have the best D backfield I have seen in quite some time, they also have a very good front 7.
Now stay with me please because I might just blow the foil right off of your head.
The Broncos run a pass heavy offense.
The Broncos best running back is Moreno, he is also a big part of the passing game since he catches passes very well and is an excellent pass blocker. He was injured for most of the game.
The Broncos pass blocking has not been tested thoroughly since Manning gets rid of the ball so fast.
The Broncos WR usually get YAC since there is an added emphasis on rushing the passer as well as not facing a defense that defends the pass as well as SEA.
Now when you look at facts instead of assumptions it is easier to come to logical conclusions.