Let's put aside the fact that these are all gang member scumbags and that they allow fish-hooking and eye gouging (haven't seen anyone bite anyone.....yet):
The fact that it happens on concrete honestly takes away from the fight.
You can trip and fall and knock yourself out cold on concrete, so hitting a guy just hard enough that he loses his balance and KOs himself by bouncing his head off the floor or just taking him down with a simple double-leg where he does the same, doesn't prove any skill. It introduces too much luck imo (e.g. that you don't bang your head as opposed to your opponent defeating you). I have seen a guy sprawl on a double-leg and then start sitting down hard on the guy's head just to bang it against the concrete. That's weapon fighting.