Serious question, have you watched much of Duke this year? I'm basing my opinion on watching him score in the half court this year. I've been surprised by his ability to slash, score in traffic, and of course get up for 2nd chance points and rebounds. I'm not saying that'll be just as easy in the NBA, but I don't see his performance this year as solely fast breaks, which is what I assumed he'd be held to coming out of HS (many of the fast breaks he created from his defense, for what it's worth).
It could also be that he's not really that effective in the half court... it's solely an opinion based on watching him and possibly me having a low bar in terms of expectations coming in. I've caught only a handful of Duke games, but they're generally the ones against top teams. So, my perception could be off base.
ETA: I'm not convinced he will be transcendent or the next LeBron. That is a high bar, and like you he'll need to show me something to earn that praise.