I think weight is a big concern - 23 years old and only 222 lbs. That is not a playable weight as an NBA center. He also tested as a worse leaper than the 260 lb version of Kanter, pretty bad. A team like Miami who is desperate for a center would probably love to get him in the late first round if they could buy Phoenix or OKC's late first.
Correct. Withey is very slow, soft, and has about an anthill's worth of offensive skill. I'd be shocked if he ever gets significant minutes in the NBA. He would need to develop a lot.