We will never know the "fight" in the attacker. Some people will break off an attack at first injury...some will fight to the death. Same way with the good guys.
To me, if the BG is leaking hydraulics...that's a good hit. I would prefer him to be leaking from both sides, above the waist.
So, a bad hit is if he is still in the fight. Shoot again, hit him better/harder/more often! Stop the fight.
I have never been in a shooting fight...don't want to. This is all theory.
Mark