system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can MMA fighters often handle multiple blows to the face, but go down if they get a punch to the liver?

I have always wondered why this is the case. I’ve seen the most hardened fighters go down due to a simple kick or punch to the liver. Hope someone can explain this phenomenon to me.
gpt
Your skull is really good at deflecting and absorbing impacts without actually taking anything beyond superficial damage.

Getting hit in the face is painful and disorienting, but if the force isn't sufficient to actually cause a concussion or fracture there (usually) isn't actually much damage.

The organs below the rib cage don't enjoy the same level of protection.  Your brain, heart, and lungs are well defended by bone armor but the lower organs are exposed.

Blows there can cause organ damage, forcefully empty the lungs, and/or fracture the "floating" ribs that aren't anchored to the sternum, all of which will drop even a skilled fighter if they take a bad body blow.