I don't care that much about Eiserman's defensive game. Either he can fill the net and his scoring outweighs his d zone play or he's not an NHL player. Yes, you want him to work on it of course, but no amount of improvement is going to change that.
He definitely did not have a dominant season. If you used a grading scale of
A - top 3 player on the ice
B - positive impact
C - nonfactor
D - negative impact
F - liability
How many A games did Eiserman truly have? Not too many. Probably the BU game (where half the game was unwatchable!) and maybe a few other games. I would put that number less than 10 for sure.
Stats wise, he scored the 2nd most goals ever by a U18 player. 25 of the 58 goals came on the powerplay. He's obviously a shooting threat and if this player will have any value to you in the NHL, he will play on your powerplay. Even strength, he still led the team, Eiserman had 33 ES goals and Hagens had 32. It was more of a good season than an all time season in that sense, simply just talking production.
Which leads to the linemates argument and there I agree. For the most part, he played with Bednarik and a revolving door on the other wing that settled as Max Plante. Neither Bednarik and Plante are a lock to ever play a NHL shift and probably top out as middle 6ers. None of three could drive the line, they had poor chemistry, and the line was often ineffective. So that hurt Eiserman, but you'd want a top 5 / top 10 pick to be able carry a line like that.
Development wise it's concerning. How effective is he right now and how much better do you expect him to get?
You add it all together and I think you're left with a player who will need to be a 3rd wheel finisher on a scoring line. Someone who isn't a puck carrier and focuses on finding the soft areas. He doesn't make his linemates better other than drawing attention away. He is not dominating the puck. In the right spot, he can score 35+ goals a season, no question. That's not a foundational piece, but still a valuable player. If he's not scoring, he's this line cancer player that ruins any momentum a line can sustain.