He hitched his wagon to one of his best friends. Personally, I can respect it. But professionally, it was his death knell.
Also, he made a grave mistake hiring Coley to run the offense (although several coaches after him have as well). He prioritized recruiting, which is fine, but as a defensive minded coach, giving the keys to half your team to James Coley obviously is a disaster.
But his first 2 years, he brought in Jedd Fisch, which was clearly an intelligent move. And in 2011 and 2012, under Fisch, we had pretty good offenses both years. We struggled in the redzone in 2011, but we moved the ball very well. And in 2012 we averaged over 30 points a game.
Once Coley got control, it was just a steady decline.