I don't believe in game-fixing in the NBA although there were rumors that there is a syndicate that is inside the NBA doing such a thing although there was concrete evidence about it, when I was in high school there are rumors circulating that the reason MJ father died is that MJ refuses to drop the game, which I think is speculation, I'm not sure.
We can't talk about evidence because there was really no evidence, otherwise NBA would not anymore exist now.
As big as they are, they also have big influence and they will do everything to keep their good reputation as that is the only thing that makes them attract people to like their league, everything is just a speculation, but it's good to see some speculation as it makes the league exciting to bet.