I don't think I've ever seen Hamed seriously hurt (a little swelling in three fights, a couple of bloody noses, and that's it, aside from the damage to his hands - which he did to himself, rather than having it done to him by his opponents), and in his 37 pro fights, he fell down many times, but I don't think he was actually knocked down more than 6 times.
I don't remember ever seeing him wobbly after a punch, even a knockdown. In fact, if you watch his first 20 fights, you'll keep hearing the commentators saying that they wonder what will happen when someone finally puts some pressure on him or hurts him, because it hadn't happened yet.