He's not just punching people quickly with human strength.
Imagine a friend of yours, stuck the top half of their body out a car window, and then the car charged at you at 88 mph... And then that person with their torso and fists hanging out the window, propelled at 88 miles per hour, punches you as hard as they can as the car passes where you are standing.
Is the effect on your bare chin going to be less or greater than if this friend of yours were just standing in front of you at rest and winding up for a haymaker?
Your friend would end up with a badly mangled arm/hand.