I'm a college bb fan first and watch these kids (from the recruiting standpoint) from the time they're sophomores in high school. Warning, however, is I am HUGE UK fan .. so having said that ...
Williams - Tweener, for sure. Very little chance he can play stud-level NBA ball at the SF position.
Kanter - Yes, there are questions about his knees. However, I watched (live) MANY practices early last year and he had no problem whatsoever .. HE WILL be dominant.
Knight - There are legitimate questions regarding whether he is a true PG. However, he's a freshman and played on a high school team that he was the ONLY scoring option (and he averaged 36 per game). As last season progressed, he started looking like an elite PG. He also hit TWO game-winning shots in the NCAA tourney. Helluva shooter, scorer, and a very cerebral guy. He'll be a winner.
Having said all that, I think Knight at #3 is too early .. not terrible, but too early. Kanter is a steal at any number, period. I see Irving as the CLEAR absolute #1 in this draft, maybe not even close .. and I HATE duke.
Kanter will not be buried in the line up, by the way, he's 'that' good.
*Kanter*