The team would be crazy to trade him for less than a high value piece, and his fans should not have to do selective stat dives and point out subtleties to show his value. There's lots of room for improvement in his game.
But sort of indirectly you've shown why those "selective" stat dives are used by people, namely because the people who aren't inclined to give him credit for much and haven't been over what everyone in the world would agree has been a less than ideal start to his season dismiss what the actual numbers always said about him.
His production, for instance, was never "bad". He was never on pace for point or goal totals that anyone would look at and say "Man, what a crappy season for anyone relied on to be a secondary scorer on a good team" but when you would point that out in relation to the criticism he was facing you'd get "Well, it's not really about the scoring numbers but the other things".
So it's not that anyone ever needed to bring up his possession numbers to establish that the criticism was over the top it was that the people criticizing him didn't want to hear "He's still on pace for 20 goals and 60 points over 82 games which is pretty good".
As for the rest of it the "less floating" or whatever, again, I don't think that strictly speaking anyone ever needed to bring up his advanced stats to show that regardless of what sort of labels his critics wanted to apply, generally good things were still happening with him on the ice but if you used the other argument of "The less floating/more intensity crap has been said about every single offensively talented player on the Leafs during their slumps dating back to probably Vince Damphousse and wanting Nylander to become Ryan O'Reilly is not a legitimate standard to hold him up against" well, again, it would mainly fall on deaf ears.
