You don't think a player that's tall and long enough to play PF (or even C) that effectively plays PG and is about high school age has extraordinary upside? And you don't think there's extreme bust potential for a player of that size that effectively plays PG, except isn't a good shooter, can't/doesn't play off the ball, has a very sleight frame, might not have a defensive position, and has been playing against crap competition? I wouldn't say he's exactly a risk if available at 21, but there's a real chance that he's just not an NBA player. If he can guard on the perimeter, can a reliable spot-up 3, and/or add considerable strength then he'll be a lot easier to work into a rotation, but I don't think those are there yet.
I'm all about drafting him if he's available at 21 but again, he might not be an NBA player. I think it's worth the... well... risk to find out.
This is a good post, but.... first of all, if you look at Giannis' physical tools and how quickly he's developing, I don't think he's a big risk. I just don't. He's got the tools and the desire (so far) to be a pro. He has abilities like court vision, mid-range shooting, slashing, timing on defense, touch around the rim, etc. to be an NBA player. I don't think his floor is that low, such that he'd be a total bust. He just needs to mature and continue to work. I think it's pretty certain he'll be an NBA player.
At the same time, he has some extraordinary skills for a player of his size and length, such as handling and passing to initiate plays and body control. What's not clear is the degree to which all of those extraordinary skills will be utilized at the next level. That's the upside question. Sure, he can handle, pass and initiate plays, but is that something coaches will want him to do, or will the coaches focus on having other players do those things and ask Giannis to focus on a more narrow set of skills like spotting up, feeding the post, and shooting off of screens? It's a bit similar to AK. AK has a unique combination of length, mobility and passing, but coaches don't want AK running plays, because he's not as effective as the guards. So AK doesn't often get to use all of his unique skills, and he has to defer to other players. AK has freakish 'upside' too, but it rarely materializes in game situations. Incidentally, this is why I was predicting that Giannis would at least play a role comparable to Michael Finley, even though it's not a good direct comparison.
So to summarize: The risk of total bust seems small. I think his floor as a player is higher than a lot of people are saying. The upside is significant, but it's unknown how much of it will really materialize when he's mixed in with a group of other NBA players. Right now, he's mister do-it-all against a low level of competition.
I think Giannis is good enough to get drafted at #14, but if Schroeder's there he might have just as much impact as a player, and Schroeder fills a position of greater need.