Other than what you mentioned (Comfort and experience) which are big improvements....his forecheck is much, much, much stronger. He gets after it in the offensive zone and gives defenders the business almost as relentlessly as these two freshmen who we're all falling in love with quickly (Adam Shemansky and Matt Mangene)
He does look stronger, and more willing to play the body...but he definitely has another year or two, MINIMUM, to try and bulk up and get his size and speed up enough to be effective at the professional level. Even though they said "they feel comfortable tucking him away for 4 years"....if he continues on this pace I am positive that Detroit will try hard to bring him into Grand Rapids next year, and unfortunately, he might take the bait.
This is not simply a bias because I want to keep him for four years but I will say this....if he goes to Grand Rapids next year.....he probably won't dazzle you for at least 2 years. He is an exceptional player in the making no doubt, certainly elite at his current level with a multitude of future potential.....but if he signs that contract this offseason....I think he might have a rude awakening.
I think he's in the PERFECT situation to continue bulking up (he was in the coorider warming up a few times last year when fans were walking in and the guy had sticks for arms! I'm confident he's developed physically since then), continue developing his confidence, enjoy the limelight of superstar status at his current level and adapt to the pressures that come with that role as Maine hopefully gets to play games of greater importance down the road and for the next few years.
I think the one thing that is really helping his effectiveness is his common sense out there. We know he has creative stick skills....but he really shows great sense of when its appropriate to be creative, and when to stick to fundamental hockey.