Texas Tech has had a history of coaches who were somewhat abusive of their players. Both Bobby Knight and Billy Gillespie had issues on the basketball side and Mike Leach was forced out when he was accused by Craig James' son of maltreatment.
Leach's history seems to have followed him,as he ran his ace receiver off the team at Washington State, telling a story not far from James' tale. Whether it's true or not remains to be seen, but one doesn't put a NFL career in jeopardy by walking out mid-season for getting a bad stare, so something made Marquess Wilson snap and call it quits.
Coaches can change, but often, the problems that plagued them at one stop will follow them elsewhere; Gillespie had a rocky, in-your-face relationship with a number of players at UK, so the stories out of TTU weren't all that shocking. That's why seeing Bobby Petrino on the short list for the UK football job is a bit disturbing; he bailed out of Atlanta after not even a year after signing on just before Michael Vick's Bad Newz hit the wire, then being forced out at Arkansas after hiring his mistress. That kind of poor behavior tends to stick with you unless there is some sort of serious repentance.