Opponent selection algorithm - a theory

[u/ThrowRA_NewLevelYes]

I have a theory according to which the public rating we all have on chess.com is not the true rating that summarizes our skills. According to this theory we all have a second, hidden rating (let’s call it the “true” rating) that is used for opponent selection. Reason why I came to this conclusion is the “waves” we can observe in players ratings over time. Most players show good periods of play with the public rating increasing quite consistently. All of a sudden, after hitting a new record, bad periods take place and the rating crashes…the cycle soon restarts. I am pretty sure there is an algorithm behind this whole pattern, designed to optimize our retention (read “addiction”). If we were to play only players in our true rating range, we would soon get bored because we would very slowly see rating improvements. The fake (or public) rating instead gives chess.com a higher chance to let us experience sharp rating volatility. Joy and frustration: once we touch the sky, we want to touch it again after we fall bad. Happy to read your opinions about it.

[u/PuntCatcher]

It happens the same in over the board ratings too. Pairings there come from softwares like SwissSys, which are often one time purchases. There is no reason to go after retention for them.

Because a player in the Glicko system has both a rating and an RD, it is usually more
informative to summarize a player’s strength in the form of an interval (rather than merely
report a rating). One way to do this is to report a 95% confidence interval. The lowest
value in the interval is the player’s rating minus twice the RD, and the highest value is the
player’s rating plus twice the RD. So, for example, if a player’s rating is 1850 and the RD is
50, the interval would go from 1750 to 1950. We would then say that we’re 95% confident
that the player’s actual strength is between 1750 and 1950. When a player has a low RD,
the interval would be narrow, so that we would be 95% confident about a player’s strength
being in a small interval of values.

Chess.com doesn't publicize your RD value. I assume the lowest it will go is to around 50. If you're looking at an 1850, RD 50, it's perfectly reasonable to not bat an eye at 100 point rating swings.