Dante Exum is a mystery.

There are videos of him galloping toward the rim and finishing with thunderous dunks, displaying his off-the-charts athleticism. But outside of those YouTube clips, the 6-foot-6 point guard from Australia is an unknown in the United States. And it was set up that way.

The 18-year-old has been held out of a competitive team setting since leading Lake Ginninderra Secondary College to the Australian National High School Basketball Championships title in January. It has been even longer since he competed in an international setting - July's FIBA under-19 World Championships.

As a result, Exum, who has links to the 76ers, is probably the biggest question heading into the NBA draft next month.

"I guess they all have an idea what I'm about," Exum said Thursday of NBA teams while in Chicago for the draft combine. "They've seen some of the college players play 40-game seasons, and they haven't seen me a lot. So I guess when they are trying to look at tape, they can't see a lot of tape of me."

While those tapes are impressive, several scouts wonder if he'll be able to make a successful leap to the NBA.

Dominating Australian high-schoolers and 19-year-olds at a world championship doesn't compare to what other top draft prospects - Andrew Wiggins (formerly of Kansas), Jabari Parker (Duke), Joel Embiid (Kansas), and Julius Randle (Kentucky) - did last season as college freshmen.

But at the same time, Exum hasn't been scrutinized the way those four players have.

"They have their advantages and disadvantages, because [scouts] haven't seen me since last year, July," he said. "It works both ways."

The Sixers arguably know more than any other team about Exum because of his relationship with coach Brett Brown.

Brown coached the Australian national team. Three years ago, he invited Exum, then 15, to the Boomers' training camp. And when Brown was an assistant with the Melbourne Tigers, he coached Cecil Exum, Dante's father.

Exum is regarded as a player with a huge upside, but one who could also be a major bust.

He moved to Los Angeles in February to participate in two-a-day workouts in preparation for the draft. There have been reports that Exum has struggled during those drills. One NBA front-office executive said he doesn't believe Exum is capable of playing point guard in the NBA.