No doubt about that. I remember seeing a photo that was taken of Joe Frazier getting hit with one of Foremans uppercuts, and it lifted him vertically about 6 inches off the canvas before he went down. Frazier once said, "George had fists like wrecking balls."'
Shavers did have s higher K.O. percentage at 91% versus 89% for Foreman, but what really set George apart as a puncher was that he could also take a good punch, and in 81 pro fights, he never failed to go the distance, except for being stopped once by Ali.
I remember watching that live, it was really startling.