What GD said. It was in his head. He hasn't resurfaced on another team. No surprise why.
If it was in his head then some team would have believed it could coach him up.
It was in his ass. When you can't hold up to a bull rush then you are susceptible to every pass rush move because you have to set to absorb the initial push.
I saw it in Spriggs repeatedly. He would set to take a push and when the rusher did something else he was dead. And when he did get a bull rush he got run over.