I agree with most of that. He got the defense to play hard and be intimidating, which was his calling card for most of his career. The reason for his downfall is well documented -- his refusal or inability to adopt a modern offensive system. I think he might've still been a viable NFL defensive coordinator, but his atrocious, embarrassing performance on Hard Knocks made him look like a complete fool and has come to define his career.
That noted, I'm still interested and curious to see how he does, just as I am interested in seeing how Goff or any other significant ex-Ram does.