Something happened at the administrative levels of the university that sucked the mojo out of him (President Bateman?) and he saw the writing on the wall, that's why he left.
I truly believe that if he would have stayed on we would have been a lot closer to getting into the Big XII at some point prior to the 2011 almost-demise of the Big XII and before the political climate changed on the LGBTQ issue.
GO COUGS.