People mistaken slickness for defense. The problem with these fighters is that their reflexes spoiled them against low-level opposition, so they keep their hands low. A lot of these "slick" fighters keep one hand at the waist instead of both hands up. That's why they keep getting caught against fighters with good timing and fundamentals. Mayweather mastered the shoulder roll defense, but still keep both hands up in times of trouble (Corley, Mosley, etc). He learned his lesson from fighting Castillo that you can't just relying on dodging shots...you have to parry them too.