I think the issue probably is we do have a baseline for NBL to NBA transition. Giddey and LaMelo Ball were starters, putting up decent numbers, albeit on ordinary teams. Jae'sean Tate was in the MVP conversation.
Terrence Ferguson struggled for consistency, but keep in mind he had the length and athleticism that projected him as a 3-and-D player, had looked promising in the high school All-Star exhibitions, and heavily recruited by some pretty big NCAA programs. Potential May have gotten Ferguson a gig, but it appears it hasn’t worked out for him (for OKC he could work in that Sefalosha/Roberson role, but a better shooter, though it was a lot of "stand in the corner" which never developed his, granted limited, offensive game).
Personally, and glad for the kid to prove me wrong, he hasn’t exhibited what the likes of Giddey and Ball have, and although probably comparable to what Ferguson produced here, lacks the athleticism that NBA scouts highly value.
But who knows, Mitch Creek projected similar early on (though he did tick the athleticism box somewhat), and he got a call-up, so it could potentially happen. Travers, given his age, probably is as good a bet as any homegrown Australian to make it though.