A number for skill
A matchmaking rating is a single number estimating a player's skill so the matchmaker can pair similar players. The classic basis is the Elo system, originally built for chess.
How Elo updates
Elo computes an expected score for each player from the rating gap, then nudges ratings toward the actual result.
- If a higher rated player wins as expected, both ratings barely move.
- If an underdog wins, the upset moves both ratings a large amount.
- The change is scaled by a constant called K, which controls volatility.
So beating someone far above you is worth many points, while beating someone far below you is worth almost none.
Beyond plain Elo
- Modern systems like Glicko add a rating deviation to express uncertainty for new or inactive players.
- High uncertainty lets new players climb or fall fast until the system is confident.
- Team games derive a per player update from the team outcome.
Key idea
A matchmaking rating like Elo converts outcomes into a skill number, moving more on surprising results so it converges to true skill.