My take would be less "does/doesn't belong" and more "is a capable backup" versus "is still a project."
Nelson is 19. His speed and technique aren't at issue, really, it's his intelligence and read of the game. Most forwards and wings build on that knowledge into their late 20s.
If he gets to 23, 24 and hasn't yet become a dependable second-string player then he's on the doesn't belong pile, a la Tsubasa. Until then a team needs a 30 man roster to be a competitive as possible. So that's seven or eight past the main squad where you can afford developmental patience.