Scamming on prop bets, like Rozier appears to have done, I would think is pretty easy to catch. If suddenly there is an uptick in action on Terry Rozier going under 15 points (or whatever) the books can see that. Maybe normally, there is $10,000 being bet on Rozier props but then suddenly, for one game, it jumps to $300,000 and in that same game, Rozier limps off the court in the 1st quarter with a mysterious injury. That is going to stand out to the books.
So for this reason, I don't think this type of scamming is rampant. Betting on the outcome of games, over/under, point spreads, would also have the same issue. If there was a sudden increase in the action on a particular team or ref or something, it would show up. And I think you would need to have more people involved. Can one ref for example, make sure a team wins by a certain number of points? Can one player? Seems harder to do than the individual prop betting manipulation. One player can make sure he doesn't get more than 5 Rebs or whatever. Or limp off the court in the 1st quarter.