I am a fan of the UFC, although I think many people get confused about the differences between pro fighters and normal people and the applicability of the UFC fight style to “real” fights that go down in bars or streets or during a home invasion.
But still, it was interesting to see in these UFC stats. how many knockouts there were. I suspect that many of the decisions (the other high number) are based on wrestlers and/or BJJ specialists doing lots of takedowns and controlling the action (but not finishing), but you still have a better than even chance of getting knocked out with a head strike.
Even in the highly controlled conditions of the cage, which I think favors grapplers. You have to be really good at takedown defense or you are generally going down. In a bar or on the street, a vicious fighter has many more terminal options at their disposal. Many Wing Chun hits are on the end of the action, when the head hits something else besides the fist. Like the ground (wall, curb, table, glass, car).
another factor is that slow or inefficient grappling stops the fight and the guys get back on their feet… A bonus is given to the best “finish” of the night and it is close enough to always be a knockout.