ELO and ranks

Every ranked match moves two ratings for each player: their rating on that kit and their global rating. Both are ordinary Elo, both live in practice_player_season_stats, and the global one is stored under the kit id global.

The nine ranks

ranks.yml ships with nine, each starting at an MMR and carrying its own K-factor:

Each division is 100 LP wide, so Copper spans 400–799 as Copper IV, III, II, I. The top three ranks have no divisions: their LP just counts up from the rank's floor.

New players start at elo.starting-mmr — 400, which is Copper IV.

The formula

Standard Elo with a few practice-server adjustments:

expected = 1 / (1 + 10^((opponentMmr - playerMmr) / 400))
delta    = round(K × (result − expected))

K is the K-factor of the rank the player is currently in — high at the bottom so new players find their level quickly, low at the top so a Legend's rating is stable.

Placements

The first placement-game-count ranked games on a kit — and separately on the global ladder — use a doubled K and skip both the cap and the asymmetric reduction. A player's placement games move their rating hard and fast, which is the point.

The asymmetric reduction

When a higher-rated player loses and the gap is more than elo.asymmetric-threshold-mmr (200), the loss is reduced by elo.asymmetric-reduction-per-100-mmr (5) for every 100 MMR of gap beyond the threshold, and the result is bounded so it can never cost more than elo.asymmetric-min-loss (5).

In practice: with the defaults, a player more than 200 MMR above their opponent loses at most 5 LP, and by a gap of about 700 the loss reaches zero. It exists so that a high-rated player who keeps getting matched down is not punished for the matchmaker's choices.

The winner's gain is unaffected — only the loss is reduced.

The demotion shield

A loss can never drop a player below the floor of the division they are currently in. Losing at Copper II with 40 LP takes you to Copper II 0 LP, not into Copper III.

The shield only applies while you are above the floor. Once you are sitting exactly on it, the next loss demotes normally. It does not apply during placements.

Ratings also never go below 0.

Boosts

An admin can multiply a player's LP gains for a while.

Durations are written as 1d, 12h, 30m, 90s, or combined: 1d12h. The multiplier must be greater than 1.

A player's effective multiplier is the higher of their personal boost and the global one — they do not stack. It only ever applies to a winner's positive delta; a loss is never boosted, and the bonus LP is reported separately in chat.

Personal boosts survive a restart. Both kinds are cancelled by a season rotation.

Anti-boosting

Two checks, both consulted before the queue pairs anybody:

Adjusting ratings by hand

/epc stats set <player> <kit|global> elo <value>
/epc stats add <player> <kit|global> elo <amount>

See stats for the full field list. /epc → Data Management also offers Reset kit ELO and Reset all ELO, which put every row of the current season back to elo.starting-mmr. Previous seasons and the lifetime tier are untouched.