Dude, I don't mean to disrespect you, but are you trolling me? I just said that the example you gave shares nothing in common with Green Bull's situation. Kaidou didn't mention or show any signs of pain with sounds like "Urgh" or "Hrng" during Luffy's attack. The only thing they have in common is that they both fell, but being knocked down doesn't necessarily mean that you suffered damage - those are two completely different things.
In Green Bull's case, he showed signs of suffering both during his fall and even in the subsequent panel through his words and action of rubbing the affected area.