Wow...Thornton is an absolute athletic freak, and Australian players are severely lacking in athleticism.
If Thornton goes to the NBA, he's going to absolutely dominate. I'm talking basketball GOD status haha
P.s.
Yes, I live in Australia.
Just say " NO!" To drugs 
Have you not seen Thornton's numbers?
He averaged 19 PPG in college on 40% threes and >80% free throws and he put up some historically good pre-draft numbers at the combine. His lane agility scores, vertical, etc were off the charts.
Not sure if you're familiar with the Australian NBL league, but the guys there are hardly the most explosive (or most talented) athletes around. I'd argue that the average starter in the NCAA probably has significantly more talent and athleticism than the average starter in the NBL.
Guys like Patty Mills (who barely crack a roster in the NBA) are superstars in the NBL. Young Australian players with legit talent (e.g. Dante Exum, Andre Bogut) don't even waste their time with the NBL - they go straight for the NBA draft.
I know a guy for example, who won rookie of the year in the NBL and was one of the most explosive athletes in the league at the time (except for the US imports, of course). He ended up going to play in europe, averaged maybe 10-15 minutes a game in europe over 4 or 5 years, never got up to starters minutes. Came back to Australia few years ago, and he's considered one of the better guards in the league now.
The level of talent in the NBL just isn't that high. I struggle to think of players in the NBL who could defend a guy with Thornton's shooting ability, slashing ability, and outright athleticism. If he doesn't average > 19 PPG in the NBL I'll be extremely surprised.