The notion of "center of gravity" is a bit abstract in a way as you can't see it on an X-Ray... however you can see it in action in many sports. In hockey for example, you play against some way smaller guy but you can barely lift his stick or push them around (there are many at the pro level.) It's like they are 300 pounds. Though I have experienced it pretty much only with hockey, I am sure that those of you who played soccer or American football have known some rare guys like this that are "glued to the ground." We can see something similar when you do some Chinese "push-hands", a small older dude can't be moved. I know they are almost static but it is a very unique experience to realize the little won't move an inch no matter how hard you push. Regarding MMA, who do you see as having a really solid control over his center of gravity vs someone who has some trouble with their own center of gravity? I know that there are a few factors playing in like the quality of their defensive techniques, etc. but even at that, we can see some tendencies after seeing a guy of many fights. For the good ones, I will probably throw in The Dragon Machida almost on top. GSP and Aldo are great as well... BJ in is prime was pretty good to. For the not so great... I have to put Carlos Condit in there. Though he has tons of qualilties too long to list, Carlos seems to fly off the ground fairly "easily" for a top guy. Not sure that there is much he can do about that at this stage of his career.