i will take an honest crack at this although i know everyone here is messing around.
the circle idea isn't a new one, and i think its a good idea. in fact, i make my guys spar 3 on one all the time.
if you think about the purpose of a circle it can represent a small confined area. and knowing where the lines are so you don't step out during the melee of the situation is great because it forces you to do what you know in such a confined area.
imagine being in a packed club, and don't have the room to do swing or move better. if you got into a fight in the midst of them its like the same concept of the circle.
if you cross you fail......its a little harsh, but if they set the bar that high for you, then they want more out of you then you currently give them.
i've also known circles to be of people, and with one in the middle. out of nowhere people will charge you and you defend attack or what ever.
so go with it.
Hung Sing Boyz, we gottit on lock down
when he's around quick to ground and pound a clown
Bruh we thought you knew better
when it comes to head huntin, ain't no one can do it better