Why do players lose points for inactivity?
In order to keep the system accurate, it is assumed that players will become rusty when they don’t play. Every day, σ, the uncertainty of a rank,is increased slightly for all players. The increase is small enough that playing a single game will counter it ten-fold, but for players inactiave for long periods of time, it will add up. The mean value is not changed, so playing a few games will bring a previously inactive player back up to the rank they left off with. When a player is inactive for long enough that they reach the starting level of σ (typically about a year), they are no longer shown on the league table. Playing one game will place them back on.
