What the Bears are getting in Matt Nagy as a head coach is a colossal unknown. He’s a first-time head coach, promoted to a job he’s never done before. My own experience: You can evaluate a rookie draft class in less time than you can a rookie head coach. It didn’t take all that long to watch Leonard Floyd in a training camp pass-pro drill to know the young man could rush the passer (and that Shea McClellin or Dan Bazuin couldn’t), or that Cody Whitehair was an NFL offensive lineman (and that Josh Beekman or Bob Sapp weren’t).