I'm not even a big Roy fan as a coach, but your arguments for trying to portrait him as a bad coach are pretty empty. "It’s fairly obvious that he's not a good coach" is not an argument. And it’s not obvious to me at all.
From all accounts, the Quebec Remparts players loved playing for him. I didn’t hear a criticism from Islanders players. And he's got the hardware and honors, which are a much more "obvious" proof that he can make teams win.
I don't understand why do you keep dragging QMJHL kids into this. Are they supposed to say they hated playing for one of the biggest NHL legends? The implication that you would have heard Isles players complain about their current coach after not even a full year of him in charge is laughable altogether.
During his time with the Avs he lost playoff series as a #1 seed, his young core started struggling and it was all downhill after the first season. None of their young players - Duchene, MacK, Landeskog - really broke out under him, O'Reilly forced himself out of the team, etc.
With Isles, of course he has only been there a very short time and the record shows even "short shelf time" coaches manage to make their teams work for awhile. Roy, however, seems to be struggling already, of course not aided by the roster construction. Once again his top player - Horvat, Barzal, Lee - are struggling badly.
So how about we start talking about what he has achieved in the NHL rather than the stuff in juniors, huh?