There's no way any of us can know since we aren't there in the locker room or at practice to know what's being said. In many cases I would bet that a good team has a good coach, of course there are likely some good teams with bad or average coaches just as there are bad team or average teams will good coaches.
What would change to those teams if you replaced the coach? How many times do you see a team fire a coach and go from bad to good or at least much better. How much of that is from the coach, we just can't know so we can only speculate.
The reason I gave MB/Lefebvre so much heat was because you had 2 guys that were hired that didn't have 1 day of experience at their job. MB had never been a GM at any point and Lefebvre had never been a head coach before. So you don't know how good or bad they will be at their job since there is no track record. If they went in another direction and just say that somehow they could have hired someone like Guy Boucher, would anything have changed for all those prospects that didn't progress/develop? We can't know but I would bet everything I own that things would have gone at least a little better and the only thing I have to go off is listening to both talk hockey.
As for Evans of course Jeff Jackson gets credit for helping him be the player he is now, he's one of the best coaches in the NCAA. Look at
@Whitesnake's favorite team Michigan, they had one of the best coaches in the history of the NCAA (former Hab at that) and since he retired the program has been a shell of it's self.
Yet they still churn out NHLers and get top quality NHL draft picks to sign up to play there but after years of being one of the very best programs in the NCAA they have been more average of late. How much of that is on coaching? we don't know but I'll always lean on coaching is an important part of the game.