One of the lead doormen who taught me at a seminar, big guy lot's of street cred, and the smoothest big guy I've ever seen, suggested that you always drag the "not me" type friends of the aggressor into the fight. He felt that they would join in anyway so why not deal with them before they expect it, as well if you end up in court because someone got seriously hurt it was easier to say there was more of them.
He was also heavily in to avoidance and verbal diffusion but he felt that once it was on it was on.
Andrew