It's clear to me that there were serious structural problems at Auburn under Gene Chizik. They were blessed with a once in a lifetime talent in Cam Newton who essentially alleviated the underlying issues and virtually singlehandedly won the NC for them.
Chizik was probably a really really bad manager, a fact which came out this year when they had their worst season EVER.
With competent head coaches and a generally competent support staff, Roof performed average at Penn State, Duke and UCF considering the circumstances.
However, Penn State's defense finished in the top 5 nationwide in 2011 (top 20 in 2012 with Roof) which means that they had a lot experience and depth and player leadership.
UCF finished with a top 10 defense in 2010 without Roof and Roof had them at top 10 in 2011.
Duke was the same. About 2-3 spots improvement in the ranking.
This indicates that he is a person who can't make it worse but there is no evidence he can make it better.
Sadly, I feel that this is the beginning of the end.