Mentality can't be quantified so I guess that's an easy out. Mullen could just be a damn good HC and out performing someone who has never done the job before, but nah let's dismiss that point. The one with historical statistical data to support it...
Dan Mullen is a lot of things, but a bad HC isn't one of them. Pruitt is at this point not even average as a HC, unfortunately. Being aware of this and even pointing it out isn't just being pessimistic. Until he starts winning he's not proven anything as a Head Coach.