ath·lete
–noun
a person trained or gifted in exercises or contests involving physical agility, stamina, or strength; a participant in a sport, exercise, or game requiring physical skill.
game
–noun
1. an amusement or pastime: children's games.
2. the material or equipment used in playing certain games: a store selling toys and games.
3. a competitive activity involving skill, chance, or endurance in the part of two or more persons who play according to a
set of rules, usually for their own amusement or for that of spectators.
sport
–noun
1. an athletic activity requiring skill or physical prowess and often of a competitive nature, as racing, baseball, tennis, golf, bowling, wrestling, boxing, hunting, fishing, etc.
kill·er
–noun
1. a person or thing that kills.
The point I'm trying to make here, is that the comparison is just, well, incomparable. We're talking about people who participate in a martial art as a sport, with a set of rules they've been trained to uphold since the day they began practicing it. Something that must be ingrained in them as fighters, so in the great fatigue of a bout they don't slip up and seriously injure or kill one of their opponents.
On the other end of the spectrum, we have martial arts like Krav Maga and some of the older forms of Muay Thai and our own Ringen. These martial arts are for combat. They are for killing, and that is the intent given when you are trained in them. In simple terms, your MMA fighter goes for some choke... and the Killer breaks your frickin' neck.
Now this is not to say that an MMA fighter cannot be trained to kill effectively, as his body is a human weapon and he is highly conditioned. But if you put equally skilled practitioners of each in the same room, using the INTENT of their respective martial arts... there is no doubt who would come out alive. Only one would have a trained lack of hesitation to do copious physical harm or cause death.
Disclaimer: I am trained in exactly 0 martial arts, but the argument is a cerebral one, so I will continue to post
-Eric