The ROARG value
The Recent Opponents' Average Rating Gap is a computed value meant to detect players who are artificially increasing their Elo rating by only playing against significantly lower rated players.
The all-time champion of such practice in Antichess is @Teilchen, with an impressive Elo rating of 2922, obtained by only playing with 1400/1500 players. When taking a closer look at the games, Teilchen would probably lose against any 2000+ player.
How is it calculated ?
The rating gap is the difference between a player's Elo rating and their opponent. For instance, if I'm being evaluated : my Elo rating is 2003, and I play against a 1750 : the rating gap is –253.
A player's ROARG value is the average rating gap over their last 100 rated games (or fewer, depending on games availability).
So, a player with a ROARG value of –600 means they recently played with opponents whose Elo ratings were, in average, 600 beneath their own. For a given player, the lower their ROARG value, the less reliable their Elo rating.
How is it taken into account in the ranking ?
Players with a ROARG value beneath a certain threshold are considered to have an unreliable Elo rating, and therefore are excluded from ranking. The current thresholds are :
| Players' Elo rating |
ROARG min. value |
|---|---|
| Players with an Elo rating of 2500 or higher | –600 |
| Players with an Elo rating of 2300 or higher | –550 |
| Players with an Elo rating of 2100 or higher | –500 |
| Players with an Elo rating of 1900 or higher | –450 |
| Other players | –400 |
Examples :
→ A player with an Elo rating of 1450 and a ROARG value of –422 will be ignored.
→ A player with an Elo rating of 1950 and a ROARG value of –422 will be ranked.
→ A player with an Elo rating of 1950 and a ROARG value of –472 will be ignored.
Those thresholds are set to be relatively low (as in permissive), in order to avoid excluding legitimate players who might occasionnaly play against lower rated opponents. They are even more permissive for top rated players, as it is often hard for them to find equivalent players in Lichess' lobby.
Why choose such an indigestible name for it ?
Because it has the word roar in it, because it is too long and sounds ridiculous, and because my favorite hobby is to make fun of people who use long and overly complicated technical words to sound smart.