kao has to start with body contact or very close range.
so inch power (cun jin) is very important. (inch punch with your whole body)
so the practice of rooting or downward sinking power is very important in ba ji.
tai chi stresses sprialing from dan tian and waist or circling
ba ji stresses kao
both need strong rooting and minute movement or inch power.
static posture is absolutely needed in practice.