I think Sean Payton had a lot to do with Dennis Allen hiring. Im sure Mickey Loomis had ask Sean P. for advice on who should the Saints hire as the next head coach. In Sean Payton's mind, he wourld rather see his successor fail so he can look good and be considered the best Saints coach of all time.
I think Sean P. knew tha Dennis Allen is a terrible coach. In my opinion Sean Payton is egotistical.
Dennis Allen was pegged years before Sean left as the next head coach of this team, that you can take to the bank. Sean knew what DA was, a good defensive coordinator that needed someone to point him in the right direction.