This makes me wonder how old Nappa was in Z
If he was 25 or so in the flash back, then that means he's almost 50 when he dies. It's probably fair to say Nappa had reached his peak.
Radditz on the other hand clearly hadn't.
I also wonder what the other two saiyans were like. Did they die in battle? Did they create offspring?
Hell, we're not even sure when they died.
It'd make sense if the whole "re ran intro trouble on this planet" excuse radditz had was because he was on a planet with those two older saiyans and they were killed.
It'd at least make sense why Vegeta seemed to conquer the planet so easily while Radditz was gone. I'm not even sure that was the planet Radditz was referring to