People DID think Nagy was "brains" enough to hire as a HC. Same with Brad Childress, Pat Shurmur and Doug Pederson. But not Bieniemy. Must just be a coincidence.
Honestly, it's really weird the way NFL teams hire head coaches more like they're casting a role in a movie than actually analyzing what someone can do as a coach.
It's either "leader of men-type DC who relates to the players and looks like he could still strap on the shoulder pads and play linebacker out there" or "extremely young looking and vaguely dorky OC who seems like they do nothing but chug Red Bull and watch film all night"
And the funny thing is, while that almost entirely boils down to the former being black and the latter being white, Robert Saleh is Lebanese but has the right visual vibes for the former so he passes and Mike McDaniel is African-American but has the right visual vibes for the latter so he passes.
It's a shame the Lions blew it, it would have been fun to have Dan Campbell and Andy Reid out there holding it down for the "Bob Seger song protagonist" demographic.