All I have seen of him are the highlights. Everyone seems to be convinced that he is too slow for the NBA. He is slow, that will be something he needs to overcome. But I see a feel for the game a good anticipation/reaction.
Think of an outfielder in baseball. You can be fast as the wind but if you don't get that jump on the ball right off the bat, you are not going to be a major league outfielder. If you have that ability to make the read and get that jump on the ball, you can play. If you have the jump and are fast too, all the better. There were faster outfielders than Jackie Bradley Jr., for example, but no one got a better jump on the ball.
That is what I see in Edey, he has the basketball equivalent of an outfielder who gets a good jump on the ball, but in a very large, slow body. We are talking about a second round pick who will likely get a 2-way contract. He doesn't have to be Shaq.
And I will also say that based on what I see, I think there is a chance that he could develop a serviceable 3-point shot. Think of Brook Lopez. Lopez was in the league for 7 seasons before he even took a 3-point shot, two more seasons before he made more than 30% of them. Now it is a weapon for him.
At Purdue, he had no reason to ever take a 3-point shot. But I see the coordination, similar to Lopez, that may allow him to develop a 3 point shot over time. Point is you just don't know and aren't going to know unless you are the team that takes him and then really works with him for a couple of seasons.
I have no idea if Edey will amount to anything, but that is the same for nearly all second round picks and many first round picks. I would be completely fine if the Celtics took a chance on him though.