Quote Originally Posted by tunghaichuan
To paraphrase Robert W. Smith: you can be sure that a 6' 5" 250 lb. stevedore will beat the crap out of a 5' 7", 130 lb., 5th Dan karateka. Size is a huge deciding factor, which is why there are weight classes in contact/combat sports.
I've seen average sized guys beating heavier, over 6' fighters, and I'm not only talking about early UFC (pre-weight class days) but in recent no holds barred ("vale-tudo") championships in Brazil, where both fighters are prepared for it. Not saying the fights are the most technically developed thing in the world though .

Maybe the problem is this 5th dan karateka. I've practiced it in the past and I always feel that karate classes don't prepare you for real, agressive combat or a ring (of course, there are always exceptions), unlike muay thai, boxing and jiu-jitsu. What if the big bulky guy takes you down, what are you going to do? Punch him? Of course not. A decent, well prepared jiu-jitsu practicioner, even in weight disadvantage, would have a hell of a good chance to submit the unskilled brawler here, as it was proved many times before.

In a stand-up fight, the smaller guy wouldn't be standing still waiting to be punched (if he's prepared). He's going to move around all time, hit and escape to wear the bigger, usually slower guy out and look for the best opportunity for a precise strike.

Now, if both are equally well trained and one of them is a much bigger guy, he will definitely have a huge advantage.