As far as we can tell, the first four picks in the NBA draft are pretty well set in stone. The Cavaliers (or perhaps the Timberwolves, if Cleveland gets desperate enough to trade Kevin Love without assurances he’ll re-sign) will take Joel Embiid or Andrew Wiggins. The Bucks will take either Jabari Parker or whichever of the Embiid/Wiggins combo remains. The Sixers will take whichever of the Embiid/Wiggins/Parker combo is still in play. Orlando will take Dante Exum. Then the real intrigue can begin (until Adrian Wojnarowski ruins everything for everyone by tweeting the picks five minutes before they happen).

But HOLD UP. DraftExpress, the premier site for prospect info and rankings, posted a new mock draft today and things look a little strange.

Yep, DraftExpress has Orlando taking Marcus Smart. This makes some sense. The Magic already have Victor Oladipo in the role of shooting-guard-who-can’t-quite-play-point-guard, while Smart may be a reach at four, he is also a pure point guard who might match their needs a little more closely. Then Utah takes Vonleh, since the Jazz have a pair of young guards — Trey Burke and Alec Burks — which I guess precludes them from taking a talented prospect that has been compared to Penny Hardaway and Derrick Rose? I don’t know.

Regardless, this would be a massive steal for the Celtics. Exum is not quite NBA-ready, so he would be a bit of a project, but a week ago, nobody thought he would still be available at #6. Exum has the body and athleticism to become an elite wing defender, and he’s fantastic at scoring around the rim. His body control and soft touch allow him to convert in difficult situations, and he can draw fouls extremely well. His jumpshot is currently suspect (Hi Ron Adams!), and some scouts question whether he is good enough at distributing the ball to be a true point guard, but if he became a secondary PG to Rondo, he has the size to defend shooting guards in the NBA (think, perhaps, Eric Bledsoe’s role in Phoenix this season only with a taller and longer player).

We’ll talk more about this possibility at some point, but for now, feel free to familiarize yourself with Exum’s strengths and weaknesses with his entry in DraftExpress’ indispensable breakdown video series.

Meanwhile, at 17, DraftExpress has the Celtics taking UCLA guard Zach LaVine. As Ryan Hebert and I discussed on our recent podcast, I love this idea. Lavine is exactly the type of incredibly high-risk/high-reward candidate that makes sense at number 17. He’s incredibly athletic and would be able to splash 3-pointers at the TD Garden from Rhode Island, but his basketball IQ has been questioned and he will need to put on weight, as he has been described by scouts as “frail.”

That being said, Zach LaVine can LEAP.

Dunks on dunks on dunks. I’m all in.

Follow Tom on Twitter: @Tom_NBA.