It sounds like what was happening was not a matter of changing the outcome of matches. That would have drawn immediate complaints from the player(s) being disadvantaged if he had recorded points for the wrong player.

What he was probably doing was to delay the recording of some scores in the electronic system, so that his paymasters could bet on the result after it happened but before the bookies knew. In horse racing, this is called past-posting (wagering after post time).

This is not confirmed.