Humm, agree to a point, but, I did some MMA sparring and since it was sparring, the hits wasn't that hard. But, even a mildly hit on the temple or near it can really mess with you.
So, it can totally happen that a punch at the right place, even if it wasn't that hard can make you go on your knees and being totally lost for 1 or 2 seconds. After that, he was kicked and punched before he can get up, so yeah, it can happen.
And like I said, when MC is prepare to a fight, it's a totally different story.