I'd say a lot of Power's issues are just in that he just generally lacks intensity and urgency. Not necessarily that the toolbox isn't there or he can't keep up with the game...more just that, he doesn't seem to want to. Plays in a lot of sort of soft, loopy ways. It feels like his superlative tools have let him play so long that way, he just hasn't learned to play a more direct game. Defensively in particular, he just takes some kind of sloppy paths and keeps some kind of lazy gaps, details are kind of lax, probably because he's always had the tools to make up for it. And still sort of does, even at the NHL level to some extent.
Some guys manage to improve that with time and coaching. I'd say Hanifin had some similar struggles earlier in his career and improved a lot in that. Other guys though, just don't have that pace and mentality in them. Which one Power is...he's still a good player either way, but he definitely has such enormous headroom and all the tools to be an absolute stud if he grasps that concept better.