Had a roommate who played for Paterno. It was well known that Paterno ran the football facilities like his own fiefdom. You may want to believe that Paterno wasn’t ignorant of Sandusky’s crimes, but that would have been impossible given the flagrant nature of Sandusky’s abuse.
But that's just it - the abuse wasn't flagrant, it was secret. The student football player that finally broke the story declared he was shocked by what he saw. So it wasn't common knowledge nor routine knowledge. Sandusky hid it.