>>102929348Power levels are strictly a measure of ki output, and stops have real meaning during the Saiyan saga where it's revealed the heroes can cause their ki to surge and more, making the numbers almost meaningless.
Physical strength hasn't been relevant since mid Dragonball, it's all been ki and ki accessories. As you say, Goku can be hurt like that because he stops reinforcing himself with ki, because he's a world class dipshit.
The only other relevant thing is martial art skill, which can firmly trump magnitudes of ki difference.
