sullinger obviously needs to lose weight. he's a far more skilled player, but because of his weight the athleticism isn't close. IMO sullinger has "bust" potential due to the weight, but i think he might have a higher ceiling than randle due to his skill level.
randle is strong and motivated, and is a sure-fire NBA player due to his hustle, strength, and moderate skill. but he got away with a lot of garbage, below-the-rim shots in college that won't work in the NBA. he's not nearly as skilled inside as a z-bo or barkley-type, and he doesn't have a jumpshot like a karl malone or david west. in the NBA he won't be able to push guys around nearly as easily as college. he plays kind of like a shorter, less-skilled greg monroe, though he's tougher.
he's a mediocre defender, and with his body type i doubt he ever becomes more than slightly above average at D.
also, he has the foot problem, which may or may not become significant.
in short, i don't get why he's so hyped. he might be a very nice role player, maybe a good starter, but i don't see his ceiling as being all-star level. guys with his body and skillset rarely become all-stars in this league, more often they're garbagemen who rebound and clean up missed shots for putbacks around the rim.