Tressel presents a fine upstanding citizen to the public at large. He writes books about his faith, talks about faith, talks senatorially in press conferences, stresses morals, etc. 95% of his life, he walks the walk. He does good things for people who need it. So many people, including Ferentz, have a high opinion of him.
5% of his life he is a cheating bastard. He is no different than many a leader before him who presents a pristine face in public, and can do some evil things behind closed doors.