Rickson Gracie, along with being the hippest man I’ve heard of, has a concept of invisible BJJ. I don’t know the man/demigod well enough to know exactly what he means, but I’m interpreting it to mean the millimeters of difference in arm placement that can be the difference between your opponent escaping and submitting your opponent, or the tens of pounds of difference in pressure between a pin from a black belt and a pin from a purple belt or a blue belt.
These things can’t be seen. They can only be felt, experienced. But these things matter.
Edit: This was actually supposed to be posted in my jiu jitsu blog, which you can find here.