Forget the Super Bowl victory. Forget the three NFC championship appearances and nine playoff berths in New Orleans. In Denver, head coach Sean Payton faces a challenge that will take more than a glamorous coaching resume to overcome. It was evident as he was fighting for words following the Broncos’ 70-20 loss to the Miami Dolphins on Sunday afternoon — one of the worst in NFL history. Against Miami, Payton might have been at his most vulnerable.