The dude never started a game and played only backup minutes at Virginia, so it’s easy to see why he was surprised. I’ve seen plenty of freshmen non-starters get drafted on potential, but that’s a MIGHTY rare thing for a senior career bench player to get drafted.
But he does have one elite skill (shot blocking), and apparently that one skill was enough to get someone to take a chance on him. And the very fact that he was there in attendance shows he knew there was a real chance this would happen.