Doesn't surprise me at all.
He wrote a book on leadership (super Christian in its writing by the way). Old school, steeped in his religious beliefs which worked fine for him as a player but I don't think he can adapt to new generations. He only has one "tool" to work with and coaching is about many ways of reaching your players: giving the ways to win and being bought into by everyone regardless of delivery, tone, different beliefs, etc.
It's a skill set that I have long suspected he cannot even begin to comprehend how to pull it off. He is not alone either. Ditka would fail if he was the same temperament and coming up in the NFL now - he would faceplant with a losing record even if he had a contender like NE, KC, NO, BAL,et al