The fact that I don't really think he likes or wants his job. And it shows. Apathy bleeds into everything and the team gets lackadaisical about the details:all the penalties, mistakes, bone-headed errors, general sloppiness.
Now, if Bronco had a major attitude change: Embraces the fan base. Shows some passion. Takes responsibility. Stops making duplicitous statements that make no sense. I'd love to have him stay. But he's got to show that he wants his job.