Actually not true, though you do need a solid skill difference. In college wrestling its not unusual for 150 pound varsity guys to rag doll new heavyweights just out of high school. Of course, that ends when the heavyweights get their skill levels up.
And of course, against someone with no training, its pretty easy to ragdoll guys much bigger.
Even in judo, at the highest level, top guys against top guys, it can occasionally happen. For instance, in the all Japan championships (which has no weight division, just open weight), the occasional middle weight (such as Okano - 180 pounds or Kimura, 185 pounds) would win, throwing heavy weights (often 250-300 pounds) for ippon ... and back then, an ippon meant a very solid throw like something you'd see in a kata. Of course, you'd better be a one in a few million athlete if you plan on doing that (meaning you better have a nervous system which allows you timing that most of us are never going to achieve no matter how much we practice) :icon_chee
In terms of what I see Rolls doing, as someone who wrestled in college and fought nationally in judo, his throws are judo (no surprise, they're wearing a gi, and judo throws are more effective than wrestling with a jacket on, just as wrestling takedowns are more effective with no jacket). But on the ground his movements look more like wrestling than judo. Rolls looked like a phenomenal talent; as others have said, I wonder how BJJ would have developed without his tragic death.
