I know I stated before the draft I didn't think he was an NHler (and was right about not thinking he was worth a draft pick as he went undrafted, so check mate almost everyone) and I stick by this.
He is great in juniors, but he will never make it in the NHL. He doesn't have the size, the speed, or the pure offensive skill to actually stick with a roster.
He reminds me of a undersized guy who does everything good, but nothing exceptional. Dominating the QMJHL at 19 (and 18 to be fair) is great, but lets remember the competition he is facing. Teenagers.
When the going gets tough, he will get out muscled to every puck, he won't be fast enough to avoid getting hit and stripped of the puck, his hope is to be a guy who is in the right place at the right time and score some dirty goals. This is not a core piece, he is a guy who can bounce from team to team and fill depth spots if he ever makes it that far.
The difference between him and Marner/Godtreau, is that they have the high end skill and speed. They have multiple elite parts of their game.
I don't see that in Garland.