This is what my Instructor Fabio Santos had to say regarding Rickson Gracie and what he thinks the secret to his game is. The article appeared in the April 2002 issue of Grappling Magazine (full article
http://fabiojiujitsu.com/GrapplingMag.htm).
"More than anything else," Santos says, "the most dangerous weapon in jiu-jitsu is the mind. You can't be frozen in one position or only be looking for one thing. You have to be adaptable to every situation and always be ready to change your position when your opponent shifts his. If you look at my teacher, Rickson Gracie, you'll see that he is a master of position. He always shifts positions with his opponent and he never gets caught in a place that he doesn't want to be. If there is one secret to Rickson's game, that is it. The ability to quickly change comes from being mentally flexible, and always being alert to what your opponent is doing."