I couldn't agree more. Dennison is the most useless and pathetic coach Denver has ever had. When he was special teams coach, Denver had the worst special teams in the league, when he was working with the O-line Denver's O-line was pathetic, when he became offensive coordinator Denver had the worst 3 and out record in the league. 

McCoy is a very good OC. In addition, Trevor is another year smarter with more experience. Those reasons all contribute to the success so far this year. 

However, I think it will get harder real soon. Teams will get more tape on Siemian and McCoy's offense. Before long there will be special schemes put in to deal with our strengths and exploit our weaknesses. Such is life in today's NFL.