hi clo,
no witness is claiming z hit m. so any mma skills he had were used in defence. obviously this was not very effective. not sure why you have brought this up again.
m was unharmed until the shooting. z was severely beaten with repeated blows. the swollen welts clearly indicate this. this is not in doubt. you may have missed it, but z's skull was minutely examined and revealed 4-7 nasty-looking lumps.
since those lumps had disappeared the next day, i presume they were caused by the beating rather than being sebaceous or structural. the inflammation from those kinds of lumps reduces quickly using ice.
the nose injury also confirms the type of fight this was. it was likely broken. the black eyes which showed up later are what often happens when your nose is broken.
maybe you are residually convinced by the immediate press reports that z was unscathed. the scenes at the killing show z was severely beaten.
cuts indicate battery against a sharp object. welts are what occur when the object against which the impact occurs is not sharp. I count the two cuts as likely to have occurred on the concrete sidewalk. the others from m's fists. either way, the worrying damage is inside the skull rather than on the skin. punching someone's head repeatedly is very dangerous.
any assault that creates welts may also result in a concussion or a brain injury. i have personally experienced a concussion by being struck accidentally on my chin. brains are very sensitive to strikes to the head - almost wherever they are hit, but particularly on the side and the back. the person examining z's injuries made a very clear statement that z's injuries were consistent with the possibility of brain damage. fortunately, he survived.
one witness is not going to reach the standard of "beyond a reasonable doubt" when the mass of the evidence and the rest of the eyewitness testimony indicates the opposite.