My argument is that if the head is off the ground the muscles of the neck can absorb some of the force of the blow. Having the head off the floor provides more opportunity for the blow to deflect off the skull reducing the force impacted by the strike. By yielding with the strike the period of the strike is increased this lowers the rate of acceleration of the brain in response to the strike so reducing shearing forces and tearing of tissue. If you head is on the floor your muscles cannot absorb any of the energy and there is little or no opportunity to deflect away any of the force. the moment of impact is very short resulting in a sudden acceleration of the brain increasing shear and tearing injuries. I understand the argument of cuop contra cuop injury as a result of head movement. but in my opinion having the head in contact with the floor means more force translated to the brain over shorter time period which leads to greater damage.