How ratings work
Plain-language guide to Glicko-2 ratings on Billiard Tracker.
Billiard Tracker uses Glicko-2. Think of it as a skill estimate plus a confidence score, updated after rated matches in each discipline separately. Ratings are not fixed points; they are probabilities that become more accurate as more results come in.
What rating means
Your rating is the current estimate of your strength in one discipline (8-Ball, 9-Ball, 10-Ball, Straight Pool, or Snooker). Winning against stronger players usually helps more than winning against lower-rated players.
What RD means
RD (rating deviation) shows uncertainty. High RD means the system is less sure and your rating can move more. Low RD means your level is well established and each result changes less.
- New or inactive players usually have higher RD.
- Active players with many recent results usually have lower RD.
Why new players move faster
New profiles are treated as provisional until enough rated games are logged. The current default provisional threshold is 10 rated games (can differ for custom leaderboards). During this period, rating movement is intentionally larger.
What happens after each result
After a rated win or loss, Glicko-2 compares expected result vs actual result and updates both players. Upsets create bigger changes; expected outcomes create smaller changes.
What the system looks at
Glicko-2 does not only check who won. It also considers confidence in each player's current number and how surprising the outcome was.
- Expected win + low RD on both sides: usually smaller movement.
- Upset win + lower-rated player: usually bigger movement.
- Very high RD player involved: movement can be larger for both players.
Discipline separation
Each discipline has its own rating track. A 9-Ball result does not directly change your 8-Ball rating.
Examples
Illustrative scenarios (not exact point values):
- Example A: Player A (1500, low RD) beats Player B (1480, low RD). Result is expected, so A gains a little and B drops a little.
- Example B: Player C (1420, medium RD) beats Player D (1600, low RD). This is an upset, so C gains noticeably and D drops more than in an expected result.
- Example C: New Player E (1500, very high RD) wins first two matches. E can jump quickly at first, then movement naturally slows as RD drops.
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