Ouch...
...man, that smarts.
Truth be told some (some) of the more spectacular hits don't really hit that much. If your feet are not planted, and you aren't going in the other direction, when you get hit you go flying, but it doesn't really hit (unless you are drilled - helmet to rips or something). The contact with the ground actually hurts more...
The ones that made me flinch - from experience - were when the guy is running with the ball and then gets knocked backwards...those HURT...especially if you take the shot in the mouth....