system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why does a helmet-to-helmet hit only hurt 1 player?

Just saw the hit on Rob Gronkowski. Just wondering why he has to leave with a concussion while the other guy is unharmed? What’s happening here?
gpt
The defender is usually in a position in which they can deliver that blow with the crown (forehead) of the helmet. The neck is strongest against being bent backwards and the defender is prepared for impact in that region. On the flip side, the offensive player’s neck is going to snap one way or the other. There’s really no way to prepare for and lessen this impact. This is how concussions and spinal injuries occur.