Mcavoy had his 1st goal, 1st assist, played 22 minutes, and was the 1st star of the game according to Nashville's broadcast in his 1st regular season game. I remember Werenski's 1st game, it was against the bruins, and both he and Mcavoy had times where they looked like shaky rookies and then times where they looked like dominant vets. but McAvoy had a better debut. Not sure what game you were watching.
I believe I was watching the game where McAvoy tripped over his own feet repeatedly, made more than a few blind passes, took three lazy penalties, and generally looked unsure and uncertain. His instincts seem good, so it's not as though he has no business being out there, but he doesn't look nearly as smooth as Werenski did on debut. Like he knows what he should be doing but keeps second-guessing himself.
Granted, that's just the first game. If we went by first games only, Provorov would be a confirmed bust.
Not claiming that McAvoy is doomed, just that he didn't have a comparable debut as yet. I suspect as soon as he settles down he'll be fine. But, IIRC, Werenski didn't need such a transition period (at least, not at the NHL level).