Somebody will have to explain to me that, after there were public accusations and investigations into Sandusky's behavior decades ago while Joe was still coaching, even when he was supposedly cleared of them, after McQueary reported to Joe about what he saw in the shower, how in the hell did Joe allow Sandusky to keep his office, be allowed the run of the Penn State football facilities, bring boys with him to bowl games, etc. etc.?
At that point, Joe HAD to know that Sandusky's actions didn't pass the smell test, yet he kept him around. My opinion is that Joe didn't get the gravity of what was going on with regard to pedophilia (the most innocent version), he wanted to protect the image of his program, and once it got to a certain point, he couldn't lower the boom on Jerry, because Jerry could turn around and say that Joe knew all along...he needed to ease Sandusky out (the "retirement") and take care of everything inside the program, like he did with all the player discipline problems. Only this wasn't about some football players committing stupid and sometimes petty crimes. This was rampant and long-term acts of pedophilia. Even if some of the claims and paid claims were sketchy, there was a LOT of crap coming down. I have a sense that Sandusky and the actions known thus far are only the tip of the iceberg.
Some apologists can assert the claim that there's no proof...but there's certainly a preponderance of evidence and a reasonable person could easily come to the conclusion that Joe and his superiors knew...and did little or nothing about it.
FTR, I don't hate Penn State. I want to beat the crap out of their football team, but it is a fine academic institution. A certain percentage of their supporters have a misguided worship of a football coach who wasn't as saintly as they'd all like to believe.