I don't recall every watching a flyhalf score 3 tries in an opening 20 minutes or thereabouts.
He is going to become a marked man for the Springboks. He was given a decent amount of space by Connacht. In test rugby he is not going to get as much time and space, but his loop around passes are able to create space from nothing. The receiver draws the man, and then Sasha angles his runs into space.
Sasha also has a very good pass, so even if the opposition commit more players to him, it will create space out wide- like the try he setup with the back pass to the Stormers winger..