Angry people are easy to predict. Easy to predict means easy to beat.

Anger narrows a person to a very small set of moves. Someone furious is no longer choosing, they are running the obvious response, which means anyone watching calmly can see what comes next and be elsewhere when it arrives. Heat costs you options and hands them to whoever kept theirs.

The useful part of this is what it says about your own temper. When you feel it rise, assume you have just become readable and slow everything down. Let the other person be the predictable one, and decide from the quieter place.