I remember a scientific American article I read a million years ago. That demonstrated that in stag beetles. Biologists wondered why there were male beetles with small horns when only the male beetles with the enormous horns were doing all the fighting and supposedly copulating with the females. Common sense just told you that the short horned males should be extinct, but statistically they formed a major part of the population. Just like you said while the male beetles with enormous horns were busy fighting each other the males with smaller horns would sneak in and copulate with the waiting female thereby preserving their short horned genes.