Just to chime in, from video of Nylander, he still looks like his usual quick, agile himself, but he now has much more competitive size and strength to him.
From where he was last summer, to what he looks like now, it just looks like his body has matured which has allowed him to put on the size and strength without losing his legs.
It's why people are excited, because Nylander has managed to remove all "small" or "weak" labels about him, and when you look at him as a player, there isn't too much to say negatively about his game now.
At this point, it's now down to the natural improvement that young players need to go through. He'll be playing center in the AHL this year, and with no reason to expect any sort of failure to come from that, it certainly appears like we have a stud center on our hands here in Toronto.
Now, as for Ehlers, his path is almost the same, though he's a winger. Once he finds that proper size, it's just down to that natural game growth.
Both Nylander and Ehlers are tremendous players, it always confused me why some like to bash on once to try and pump up the other.