Think of it this way:
You have a 10 year old and a plastic baseball bat.
He hits a wiffle ball (http://www.londonwiffleball.com/Images/wiffle-ball.jpg
) at full force and it hits you in the head. It doesn't hurt that much and you walk away, "silly kids..."
Same kid, next day, hits a baseball at your head. Same force driving it, but it's moving slower and with more kinetic energy by the time it hits your head. Hurts a hell of a lot more.
The similarities with airsoft is that a kid hitting a wiffle ball is like a Crossman shooting .12's, and a professional athlete hitting a baseball is like a PTW at 500fps shooting .36's.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.