Thelen's potential is that of a Rob Blake: a number 1 defenseman who could become a captain one day. Some consider him even better than Barker.
Radulov's ceiling is as high as anyone's in this draft, outside of Ovechkin. He reminds me of a Markus Naslund type guy. I don't like the comparison to Fedotenko, as Radulov is all skill with little else. That being said, players like Radulov either turn into superstars (Naslund, Mogilny, Bure ) or bust into role players with an occasional big year (Stillman, Berezin, Briere). Radulov would be best served to be drafted by Chicago, so he could fulfill his dream of one day playing with his brother Igor in the NHL. Without something like that to work for, he may not work hard at all, which is the biggest knock on him.