As an assistant coach with the Giants, he was a fun-loving practical joker. He was always pulling pranks on people.
When he became a head coach, he knew he couldn’t do that any more and became known as a strict disciplinarian.
When you become a head coach, one of the things you have to do is determine what kind of a persona you want to project. There is no one right answer.
I heard that Bronco was still very intense and fiery in practice. On the field, he decided that he needed to be more stoic.