Honest question: what are Middelstadt´s weaknesses (in terms of the aspects of his game scouts consider he needs to work on most in order to thrive at the NHL level)?
For starters, Mittelstadt was my FAVORITE forward in the 2017 draft. I like(d) him more than Hischier, Patrick, etc. Style-wise, I think he will end up a blend of Nicklas Backstrom & Patrick Kane at the NHL level and has 80-85 point potential in his prime IMO. So, perhaps I'm a little biased, but I think he is the exact "type" of player the NHL is moving towards. And, no, I'm not a "Sabres fan."
So, in terms of weaknesses, this is my take...
1. Physical strength. Forget pull-ups, but he should improve his lower body strength so he can protect the puck in the NHL like Backstrom does (he tends to hover and glide with the puck along the boards and marks like Nicklas does). He is also a decent-sized kid, so he won't be able to hide as much as Kane, who is tiny.
2. Confidence. At every level so far, he has been able to DOMINATE his peers. I've seen him beat 3 players on the same play - literally making them look foolish. He won't be able to do that as regularly (if at all) at the NHL level and he'll have to make sure he doesn't get discouraged when he doesn't. A lot of that will fall on the shoulders of his coaches though. I observed that with a young Erik Karlsson in Ottawa - he would take risks, make mistakes, and his coaches let him learn from them, instead of punishing him. That is one of the main reasons Karlsson is the player he is today - I firmly believe that - that he was able to learn from his mistakes without being broken down by coaches and management.
3. His defensive responsibilities. In order for him to get the TOI he'll need to be an offensive force, he'll most likely have to prove that he is at least "decent" in his own end or committed to the team plan. If he can do this, he'll be a very special NHLer, since his skill level will be world class.