i watched a few of the fights last night and it seems a lot of these fighters get ktfo from shots that dont look overly hard:huh i understand fatigue plays a big part, but one of the fighters was ko'd with a punch in the back of head, an area harder than rock after about 40 seconds:huh are som of these fighters just a bit gunshy?
The back and the top of the head are the softest part of the skull. The reason why they get KO`ed fairly easily is because there punch resistance isnt the same as a boxers.
That's not it. It's because they don't wear 8 oz. gloves, first of all. Second, in boxing, you're prepared for the punch to come and that's all. In MMA, you've got elbows, knees, feet; all kinds of **** coming at you, so you can lose concentration and not see a punch coming (which is mostly what causes most one punch KO's) because your attention is divided. Less padding and more weapons to worry about being hit with is the most decided cause for MMA KO's, not weaker chins.
That and also the fact that usually an overtly chinny boxer won't make it terribly far before he is discovered. I'd say in MMA with the right skills you can in a way.
Smaller gloves and like it was correctly posted earlier, loss of focus for the punch when there are so many other weapons to watch for.
In addition to the lighter gloves, the tiny MMA fingerless gloves don't let you block ****. You try not to glove block punches in MMA because it isn't effective at all. Another reason for the KO shots is that, in boxing, you can cover up by leaning forward with your chin down and holding both gloves tight together up in front of you (think Corrales-Castillo), making it VERY hard for someone to knock you out. The only way to get through a tight, defensive shell like that (in boxing) is to either bash through it with straights (not the way to do it) or throw hooks from WAY out in left field (or uppercuts, but the chin down renders those mostly ineffective). You can't "turtle up" with MMA gloves - the punches will come right through. You can't really be defensive in a stationary way, like a James Toney, because if you aren't actively moving/throwing strikes your opponent can just take you down/grab you/knee you/kick you, or really whatever the **** they want to do. Alot of times it looks like MMA guys seem "skittish" in the ring/octagon (watch a Liddell fight and you'll see what I mean), but they really have ALOT more to worry about than boxers. The best defense in MMA is mobility.
I believe I have a good chin. When I boxed, I was told " I could take an asswhipping". I have been hit with both 12oz boxing gloves and amature style MMA gloves and it is a world of difference. The boxing gloves allow the impact the be spread over a much larger area then the MMA gloves.
In addition to what everyone else said-4oz. gloves, kicks and attempting takedowns leaving you more vulnerable to being clocked-imagine if in boxing you could immediately jump on the guy after a knockdown and pound his face in? In essence a flash knockdown in MMA usually becomes a TKO. in boxing you get the 8 count, the ref wipes your gloves can ask you to walk towards him... big difference.
Of course ask some of the MMA haters and they'll tell it's because somehow, magically, all MMA fighters were born with china chins. Yet another ignorant misconception about the sport, but not surprising as most people who hate on MMA have **** poor knowledge about it to start with. Lots of good points in this thread on the difference between the two sports when it comes to punching and punishment.