bolt, it really depends on who the coach is on the other side of the ball.
For example: in St. Louis Dick Vermeil did what he always did...have the offense rolling. They were one of the most explosive offenses in the league. Lovie Smith was a fantastic counterpart on the defensive side.
In Kansas City, Dick Vermeil had the worst defensive coordinator in NFL history (Greg Robinson) and it showed. The Chiefs were completely one sided.
Circumstance plays a huge role in the a player or coaches career.
This year, KC has Brian Daboll, who has proven he can put a very good running game on the field and create good mismatches. As for the passing game, it hasn't been that great for his offense's, but he's had Colt McCoy and Matt Moore.
I'm not saying Cassel is light years ahead of him, because he's not, but Cassel has proven in half of his years as a starter that he can lead teams to 10 wins if there's good talent around him.
We'll find out how good Daboll's coaching is for sure, but he's coming into a place where he actually has a lot of good players to use everywhere on offense, so who knows?