Well... martial arts (at least the Kung fu I took) there are optimal places to land a strike on a target to do damage. It changes based on the kind of attack. How they translate that into the game is positional requirements.

Example, razor kick (with the side of the foot) not really something effective on thigh, targets are side/back of the knee and soft tissue.

Throws, holds, and sparring was most effective when getting around someone's defense, approaching from the front was far from optimal because you have lots more defense that way