That's an interesting system. The extent I could agree with it largely depends on how well this step - "courtsider reports [private] data that ump hasn't recor

That's an interesting system. The extent I could agree with it largely depends on how well this step - "courtsider reports [private] data that ump hasn't recorded/doesn't record" - represents the real game. I would think the courtsider and ump record scores at an almost equal pace (and the advantage a courtsider might get from guessing a score ahead of the ump by a few milliseconds is likely negated by wrong guesses). But the stuff the umpire "doesn't record," like a player's injury, can be seen by every attendant of that match. If the injury (or some other event the ump doesn't record) is seen by most of the stadium, isn't it more "public knowledge" than "private information"? If so, then courtsiding isn't like insider trading. If the stadium full of people counts as a "private" party, then it is.