Run plays are supposed to be used to set up the pass.  Running is not an offensive plan, in and of itself.  Personally, I keep wishing the Broncos would go downfield more often, but
1.  You have to have receivers that can catch and hold onto the ball
2.  You have to have a line that can protect the QB without holding
3.  You have to run in order to set that up

Therein lie the problems.  I do know that good teams throw downfield successfully several times a game.