The six degrees of freedom:
forward/back 前後
up/down　　　　上下
left/right　　　　左右
pitch(　　　　　 (ピッチ)
yaw　　　　　　 (ヨー)
roll　　　　　　 (ロール)

It’s probably one of those simple “things-I-wish-I-had-known-when-I-started“, but I found it very helpful to realize that we could move within 6 degrees of freedom in relation to an opponent.

Going back – disengaging -, is a simple concept but often overlooked by beginners.

Yaw/Roll : e.g. back-steps and hip switches, flopping on the floor and coming up for a leg drag.

Pitch : e.g. diving for a kimura-pass when standing above a seated opponent.

It’s a useful model to keep in mind. Sometimes those can be micro-movements too, like being stuck under side control, establishing basic frames to survive and exploring the 6DoF to see where more space can be created.

2020.04.03 edit
Great to see that Keenan has a similar concept in his mind!
He calls his the “Up Down Left Right” methodology.
But it is essentially the same realization that it’s a 3 dimensional game, and that it can be easy to self-limit ourselves.