I'd say that Reika and the old man are only semi-good compared to the Osakans and that they kick ass compared to the cannon fodder that Gantz has chewed up and spit out on other missions.

I think that they're about on par with the three sadists.

Sure, everyone on the team could improve but I think part of the charm of the Gantz manga is that people do stupid stuff and get killed or at least maimed for it.