Again, the question isn't wether or not he's a good OC. Being a Head Coach and being a offensive coordinator are totally different jobs. And he failed miserably as a head coach. I also can't believe people can trust him ever again after what he did to the Colts. That's as fucked up as it gets.
Belichick was an infinitely better head coach with the Browns. Shanahan, I guess, but he was dealing with a cluster **** of an organization and Al Davis' meddling. But I could name 50 coaches who failed and didn't turn into great head coaches. Just because two coaches in NFL history followed that path doesn't mean McDaniels will follow suit.
But I guess some Bears fans are intent on proving it can get a lot worse than Matt Nagy.