Ten lessons learned watching a Duke practice

Williamson rocks the rim on monstrous dunk (0:27)

Duke freshman phenom Zion Williamson drop steps and tomahawks the vicious slam in the Blue Devils' intrasquad scrimmage. (0:27)

DURHAM, N.C. -- On Tuesday afternoon, I attended Duke's three-hour practice, which was only open to staffers, donors and patients of a local children's hospital and to NBA scouts interested in the trio of players -- Zion Williamson, R.J. Barrett and Cam Reddish -- who could secure the top three spots in June's NBA draft.