I think we're vastly underestimating physical strength, and grossly overestimating magical ability. 

 Contrary to popular belief, human punches are rather destructive. For the record, professional boxers like Mike Tyson more or less wield their fists like small war-hammers; if one of these guys were to hit you in the head, it would be like someone crushing your face inward with a club, most likely leaving you with brain damage. Tyron's surreal punching power is most likely derived from his physical strength, mass (throwing his body weight into the punch), his lack of 'arm punching', his act of pivoting during the punch, and his foot work. Additionally, these fighters have conditioned themselves to withstand such blows, putting them several notches above the average man or woman. Granted, such high-power impacts are cushioned by the boxing gloves they wear as well as small tactics used on the target's behalf--such as dodging and weaving and stepping forward into the punch to lessen the distance the punch travels in midair---but it's still impressive stuff. 

I believe Tyson had a punching power rated at 1,750-2,000 psi, which is nearly twice that of the bite force generated by a spotted African hyena, with this animal more than capable of breaking bones with its jaws. 

And this is at low-tier. I don't want to imagine what a high-tier rated punch is like.

EDIT: Just read what LeeRoy said on punching force versus lifting capacity. 

Sigh.