Power is a gentle, cerebral, slow-the-game down type who was always bigger, smarter and more skilled than the opponent growing up.
He never had to learn assertiveness because he's kinda been a man playing against boys and never really needed that quality. Therefore, he still gets taken by surprise at times by the speed and strength of NHL players.
He's also just turned 21 and in a lot of ways is still a boy, mentally and physically.
Some Sabres fans have turned on him for 3 reasons: he's a 1st overall pick who is not ripping up the league; he's big, doesn't hit at all and gets overpowered at times down low; their team has been bad for a long time and they need whipping boys.
What they don't talk about is how good he is at passing the puck, on the breakout, defending the rush, joining the rush, and controlling the blueline. His reads in the offensive zone and both ways in transition are very good. He doesn't get beat to the outside and breaks up plays with his stick He is also a horse who soaks up ice time and plays in all situations.
Right now he gives you good offensive 2/3D vibes most of the time for most games, but with enough high-profile errors for the haters to glom onto. His calm style can yo-yo between poise and lack of assertiveness.
The Larry Murphy comp is actually a good one and is probably the most likely end product, but the raw material is there to be even more, and Murphy is a hall-of-famer. He's a smart kid and a hockey nerd. He has high expectations for himself and will work on his game.
Their aren't many (any?) players who combine his length and his brain; both attributes are elite. His skill level is also very, very good. Barring injury, he's going to play forever.
This website has a long history of calling kids stars 20 games into their careers, then busts 100 games later despite all the evidence suggesting that it's a 3- to 5-year process, with defencemen generally being on the longer end of the scale.
Power is good right now. But once this boy has 250 NHL games of learning and 230 pounds of muscle under his belt, he's going to be a stud.