I'm not discounting the impact of the hires. They certainly have their role in this mess. But I have said before, when I was walking up to the stadium for the 2010 opener, and saw legions of people wearing Tebow Broncos jerseys, I realized we had a serious problem. The ultra-success we'd seen from '06-'09, combined with the downturn of our in-state rivals had made us the trendy team, meaning that many of the fans that were showing up weren't doing so because they loved the Gators. Rather, they were showing up simply because it was the fashionable thing to do. Then factor in the Tebow obsession, and UF completely pricing most of the diehards out of the market (thinking it would always be that good), and you get left with a bunch of newer ticket holders that suddenly don't care any more once that era had ended.
Now, add in bad coaches and their terrible performances, and you get what we have.
Ironically, I'm not sure Mullen isn't by far the best of the three hires. It's just that he was never hugely popular, and the aforementioned damage had been done.