Too soon to tell, imo.
None of the kids he's got are "his" this season, except maybe Berglund. I think Steen and Ahcan have exhibited a sea change from last season to present, but Mougenel really hasn't had them long enough to get credit. That said, the kids called up have looked ready to play in the NHL, rather than like frightened rabbits, as had been the case far too often over the past few years.
I'm still trying to figure how he's working with the defensemen. Covid and injuries have left them icing AHL lifers too often to get much of a handle on it. I feel I should be instinctively negative, or at least looking for a negative there, but I can't really nail down why. If you put me on the spot, I'd say it doesn't seem like he's pushing them enough.
Hopefully by the middle of next season I'll be able to say something more profound than, "Uh, dunno."