BB was IMO an undisputed great DC. But as a HC, I can't get past the fact that with Brady, he has a stellar record, but without Brady, he is a mediocre, losing HC. He was nothing as an HC before Brady, and nothing after, and we have reams and reams of before and after data on it.
So ... maybe the best DC ever, but not as an HC.
Note: Post title is from tweet that links article.