mostly hitting them on the jaw is to do with power!! but in some ways its more of a physical thing with it ssay u hit someone right on the button , i mean if you hit someone just fairly hard bang on the point of the chin it bangs your jaw back hard and fast enough so your jaw and other things maybe inside your head affect the pressure points near or possibly below your temple and thats one thing that happens when you see a fighter thats knocked out before they hit the ground!!