In MMA why doesn't the losing fighter swing for the fences?

Body Damage, Head Damage, fatigue, stress, and confusion prevent the fighter from throwing for the fences in the later rounds. IT's been done but only by Fighters with amazing Stamina and perseverance.

Typically the losing fighter will swing for the fences in the dying minute or seconds of the match as there is usually no repercussions....as far as being taken down goes.

Most of the time, such as in Koscheck's case, he did not go all out in the final few rounds because he was still working on his technical game plan. Swinging for the fences leaves him very open and susceptible to knockout punches, as well as being easy to take down. Hence why this is usually utilized only at the very end of the last round. It takes a lot of gas to keep this up for only a few seconds...(ever see how long a street fight lasts?).

To chip in on the GSP-Kos scenario, even when Kos was fresh and didn't have as large of eye damage, he was being made to miss by GSP's evasiness. I can recall a few moments where Kos was literally stumbling around as GSP made him look clumsy. And that was when he was fresher.

Compound the skill gap with the fact that by the 5th Kos had a swollen eye and poor depth perception (evidenced by the fact that he tried several kicks which you could tell he thought he'd land but was nowhere close to connecting with) as well as being fatigued and tired and he probably couldn't manage a final blast.

To your question in general, every fighter's different, I've seen what you talked about happen sometimes, but I've rarely seen it work. Often when one fighter is controlling the fight and the pace, even if you try to dig yourself out of that hole last minute it's probably not going to matter. In cases like that, it was earlier that you should've tried doing something unexpected, and not when the stakes were higher. All my opinion of course, I'm no expert.

They are many reasons.Think about this though,Koscheck was blinded in one eye by the 4th round..he still had to be careful of his own offense and not give the rest of the fight away by one bad miss.

Koscheck put up an awful fight overall.

Frustration.

Koscheck was already badly hurt, I mean he couldn't even see out of his eye. His depth perception was clearly off.

I do agree though that he should have tried, but it wouldn't have mattered anyway.

http://1hitquits.com/ -For UFC 124: St-Pierre vs. Koscheck