I have no earthly idea...probably because
A. He didn't want to coach here
B. The clowns that were running the show wanted OB
C. All of the above
Nobody...N.O.B.O.D.Y. turns down a job they really want because a fat, bald, Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) dude breaks a story about it on his shitty website sooner than he wanted. That's the dumbest rough ridin' theory on the planet. Yeah, he was all set to come here...was excited about coaching his alma mater...negotiated a contract that would give him a big raise...convinced his wife it was the right thing for the family...started shopping for houses...and then BOOM!!! somebody writes a story about it before he wanted them to so he totally changes his plans and leaves a couple million over a few years on the table. See how rough ridin' Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) that sounds when you think it all the way through?
Is Fitz an idiot? Absolutely...but he's not responsible for Patterson not taking the job.
I suspect that OB swooped in at the last second and Wefald pulled the trigger and told Patterson to go eff himself cause his old buddy was coming back...but what the hell do I know?