You have obviously watched him a lot as a junior to make that call?
Honestly I just think he's got a good chance at it because of his size at his age, if we could get 30-40 games under his belt by the time he's 20, it'll put him in really good stead to be a major contributor for us in the future. By all accounts he's a younger, taller, and better built version of Anthony Miles.
Not many kids have "ready-to-go" bodies at 18 years old, but the ones that do, generally end up playing pretty early on. I'm not sure of his exact size, but at a guess I think he's like 182 or 183, and he looks well over 80kgs from the pics I've seen, which is a mans body, not a kids.
FWIW, Daniel Rioli debuted last year at sub 70kgs.
Obviously there was a reason he slipped to a pick in the 50's, but from what I've read, injuries may have played a significant part in that happening, so I'm not sure. In any case, your draft position means very little once you get to the club, because if you can impress the coaches and show you're ready to go and contribute to the team, his draft position will be irrelevant.