Well I main Nasus and here's what I will tell you about Nasus.
Nasus is a freeloader.
If his mid and bot lose lane then he loses the game automatically because enemy mid/bot come camp top and he loses stacks, and Nasus is utter trash when he is behind in stacks and has no way of carrying his team if he has been prematurely cut off from his stacks due to camping.
If his mid/bot lanes win, then he wins by default because enemy team is so busy dealing with the fed mid/bot that they don't ever come top to stop him from stacking.
If all lanes go even, then he farms while his team 4v5's and if they can hold off 40 minutes then his team usually wins by default because by that time he has enough stacks to 3 shot inhib turrets.
He has zero impact on other lanes, which is why he is a freeloader. He doesn't want to teleport or roam to begin with because he loses stacks by leaving top, and he also has difficulty starting fights because he has no hard CC and is easily kited, hence it is usually not worth leaving lane for him because he rarely gets any kills or even assists out of it.
If Nasus wins game, it's not because he did well (unless he somehow won lane due to misplays on the opposing top/jungler's part. Nasus is NOT supposed to win lane. If he wins lane, then you're fucked, because he can stack freely and will never fall off) its because his team didn't feed during the laning phase and played it safe if they died in order to prevent a snowball situation.