We can't assume 100% but we can be aware of trends. I think his age, his huge jump in mock draft ranking, and concern about whether he can play NBA-level defense in some scouting reports are all red flags, but the presence of red flags doesn't guarantee failure. They do, however, make him have a lower probability of becoming a star than some of the other players who have been mentioned as possible picks at #3, but that probability is non-zero.
For a player like Hield, who is mature and has a strong work ethic, the gap between where he is now and where his ceiling is is usually going to be much smaller than a younger, rawer player. There is much less of a chance for some late physical change. He doesn't seem to be someone who is still learning his craft. There aren't glaring holes in his game which can be fixed by learning. If you think he is going to improve, you have to have an idea of how. This isn't some video game where you can just level him up with more experience (points). What is he going to do, keep increasing his three-point percentage until he's up to 58%?
It really looks like his place in the game depends on how he is going to defend and be defended by players who are either quicker or taller/longer and often both. There is legitimate risk that he might not be good enough at defense to be more than a role player off the bench. He has average height and length for a SG, which probably means below average for a starter and above average for a reserve. He didn't do any athletic testing at the combine, so we don't have any data on his vertical leap, but I think we can all agree that he is not an elite athlete. The Celtics assessment of his draftability is probably going to depend on how they assess the limits of his athleticism in a private workout.
Hield is 6'5" with 1 6'9" wingspan.
How many star shooting guards can you think of in the NBA right now who are both significantly bigger and significantly longer than that?
There is Paul George, Klay Thompson....and I'm going to need some help here.
Lets throw out some names.
* Dwyane Wade? Same height and length.
* Bradley Beal? Nope.
* Kobe Bryant? He's retired.
* Joe Johnson? He's got one foot in the proverbial grave.
* James Harden? Same height and about the same length.
* Kris Middleton? Similar size but less length.
* Jimmy Butler? A couple of inches taller, but less length.
* Avery Bradley? Nope.
* Wesley Matthews? Similar size.
* JJ Reddick? Similar size but less length.
* Tyreke Evans? Similar size and length.
I could keep doing all day long, but I think you probably get the point by now. Buddy Hield is big and long enough to match up any shooting guard in the NBA aside from maybe George and Thompson, and those guys are a matchup nightmare for ANY guard.
But either way, I will ask you this question. If you're concenred about Hield having the quickness and size to defend NBA guards, who is there that you would rather take who you feel doesn't have that concern?
Lets play a game. I will rank the top three guard prospects in the draft based on their physical attributes, and then we will allocate points for each criteria - the player with the most points at the end wins. In the case of ties, I will split the 2nd and 3rd place points in half.
Height1. Buddy Hield: 6'5" (3 points)
2. Jamal Murray: 6'4.25" (1.5 points)
3. Kris Dunn: 6'4.25" (1.5 points)
Wingspan 1. Kris Dunn: 6'9.5" (3 points)
2. Buddy Hield: 6'9.25" (2 points)
3. Jamal Murray: 6'6.5" (1 point)
Standing Reach1. Buddy Hield: 8'5" (3 points)
2. Kris Dunn: 8'4" (2 points)
3. Jamal Murray: 8'1" (1 point)
Weight1. Buddy Hield: 212 lbs (3 points)
2. Kris Dunn: 205 lbs (2 points)
3. Jamal Murray: 201 lbs (1 point)
Athleticism1. Kris Dunn (3 points)
2. Buddy Hield (2 points)
3. Jamal Murray (1 point)
Total Physicals Score1. Buddy Hield: 13 points
2. Kris Dunn: 11.5 points
3. Jamal Murray: 5,.5 points
If there is any guard in the lottery who's physicals you should be worried about, I think it's pretty obvious who that guy is...and it's not Hield.