The best base is distance control
Somebody should start a new martial arts gym called DISTANCE CONTROL
It would teach all techniques to remain outside, get inside or stay in mid-range, in addition to all techniques that allow transitioning from one distance to the other
This is the best base for MMA as it emphasizes controlling and optimizing the positioning of a fighter with respect to his opponent.
All MMA techniques require a certain distance to be effective and once a fighter becomes a master of distance control, then he can best express his grappling and striking talents.
This is a key factor in what makes GSP, Machida, Anderson, Aldo and Jones so effective and is the one key attribute that all have in common and have a tremendous mastery over.
Fighters with immense potential who never seem to realize it often fail because of remaining subpar in this domain, I.e. Pettis