I already said: "I agree that the development of single player doesn't tell us much about a coaches ability, but it does make me more interested in learning about what else he may have done."
So I'm not sure what you're still looking for here, but you really seem focused on BVG. Under your hypothetical scenario, what job was BVG hired for? If he was hired as a DC, I would say of course not. His system was too complex to learn efficiently, he was terrible at implementing it He sucked as a DC at a bunch of stops, and I'd be unhappy - just like I was when we hired him.
But if I knew little about BVG and he was hired as a position coach, for which he would need to identify and develop talent, and somebody pointed to a completely unrecruited walk-on, that never played the position and was undersized for it, and that walk-on developed into an NFL pro-bowler starting this year's Superbowl at a position that BVG was responsible for coaching, well if all that stuff that didn't actually happen with BVG happened, I think I'd be open to learning more about what else he did as a position coach.
It happened with Quinn, and I'm interested in knowing more about him. I'm really not interested in any fantasy scenario comparisons with BVG.