I agree about Vonleh's potential, I think he could easily become a perennial All-Star in the future. Its not often that you find bigs who are long, athletic and can contribute on both ends of the floor. I think he's going to become one of the surprises of this draft when all is said and done.
His IQ and passing skills may not be off the charts, but when you have either Sully or Olynyk at the other frontcourt position I don't think that's a huge problem.
He reminds me of a kind of Amare / Bosh / Hortford hybrid. An Amare Boshford?
I have no doubt he could be an effective center at the NBA level. He may only be 6'10" but his insane length combined with his combination of strength and athleticism tells me he'll play bigger than he is. Remember Anthony Davis and Demarcus Cousins are both only 6'10 - 6'11" and both have been effective at Center. Alonzo Mourning was only 6'10" in shoes and was a beast at Center.
Don't know about him being a #4 choice though. Hard to select him if either Wiggins, Embiid, Parker or Exum is still available. He'd be battling with Marcus Smart for my #5 choice...though there's a chance I'd take him over Parker (who I'm not convinced about)