Professional Snooker Elo Ratings -

How The System Works


 

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How The System Works

The Professional Snooker Elo Ratings is a ranking system for professional snooker players. It is based on the original Elo Rating System, created by Dr. Arpad Elo, which is used to rate chess players.

 

This system was modified to take into account variables from a snooker match by Stephen Flanagan to create the Professional Snooker Elo Ratings.

 

The basics of the system are very simple, and it assumes that every time a player plays a match his rating points will change based on 3 main factors:

  1. The result (whether the match was won or lost), and
  2. The strength of his opponent, and
  3. The strength of the tournament.

This means that:

  • If a player wins, his rating will always go up. The stronger his opposition, the more his rating will increase.
  • If a player loses, his rating will always go down. The weaker his opposition, the more his rating will decrease.

This is different to the official rankings which only give players rating points depending on how they performed in a tournament as a whole, irrespective of who they played.

 

This can lead to some anomolies. For example, imagine two ranking tournaments which carry the same number of points. Player A wins the first tournament, but beats the top 4 ranked players in the process. The second tournament is won by Player B (who is ranked the same as Player A), but he beats the 4 lowest ranked players in each round, as the higher ranked players were knocked out earlier on. In the official rankings, both players would get the same number of points, however, it is obvious that, basically, Player A performed better winning the first tournament than Player B did in the second tournament as Player A had to beat much better players than Player B did.

 

This is what the Professional Snooker Elo Ratings try and take into account – as well as providing a pointer as to how strong a player is in comparison to his competitors – again something the Official World Rankings don't provide.

 

The strength of the tournament takes into account the perceived value of winning that tournament, so that a player winning a match in the World Championships will receive more rating points than if he beat his opponent in a “lesser” tournament.

 

Matches are currently placed in one of five levels:

Level 1 – World Championships

Level 2 – UK Championships

 

All other ranking tournaments are placed in level 3 or 4 depending on a number of factors, such as the history of the tournament and/or the prize money available.

 

Qualifying matches are placed in level 5 irrespective of the competition for which they are played - in other words a qualifying match for the World Championship is rated the same as a qualifying match for a minor ranking event.

 

As the rating points are gained (or lost) through matches played in ranking tournaments, ratings are re-calculated after every match in a ranking tournament.  This means that a players ranking will, potentially, change after every match he plays, therefore, ratings after a particular ranking event will take into account qualifying matches for ranking events which finish later than the most recent event.

 

Finally, there may be cases whereby a player who loses a match could, potentially, lose more rating points than his current rating.  In these cases, the players rating will only be reduced to zero, whilst his opponent will gain the full amount for his win.

 

Which Matches Count?

All matches (including qualifying matches) in tournaments which count towards the offical World Snooker Rankings are rated.

 

A huge thanks to 'Jon' from The Snooker Forum who kindly provided the missing qualifying results.

 

Matches which are played in invitational tournaments are not counted in the ratings.

 

Start Ratings

Every player who plays in a ranking tournament is given a start rating. The ratings assume that new players have to prove themselves and so they will start at the bottom of the ratings.

 

Also, the manner of the rating system will tend to converge on a player's true rating after 30 matches, so any player who has played less than 30 ranked matches is given a provisional rating.

 

The original start ratings were calculated based on results in the World Championship after it reverted to it’s current knockout format in 1969, through to 1976 when the Official World Rankings were introduced.

 

Players Who Are Rated But Don't Play

If a player fails to play in a rated match during the season, then their rating at the end of the season will reduce by 10%.

 

If a player fails to play in a rated match at any point in the last 3 seasons, then they will be removed from the rating list.  If they subsequently play a rated match after this time, their rating will revert to their original rating when they left the rating list less 10% for every season they failed to play a qualifying match.

 

If a player does not play in a tournament during the season, then their rating will not change – but may well do so at the end of the season, depending on whether they've played any other matches that season or not.

 

Margin of victory

The margin of victory is not that important in the ratings, however, a factor is built in to reward players with significant wins. For example, if we imagine a match between two players (A and B again). This time Player A is the top rated player, whilst Player B has a low rating. Player B surprises player A by winning 5-4 in the last frame. Obviously, Player B gains rating points whilst Player A loses rating points. However, imagine Player B had won 5-0, a major surprise. In this instance, Player B would still gain the same number of rating points for his victory, but this would be enhanced slightly by the margin of his victory.

 

When Are The Ratings Updated

Due to their dynamic nature the Professional Snooker Elo Ratings are updated at the end of every ranking tournament. Again this is different from the official rankings which are only published at the end of the season - although provisional rankings are published from time to time.

 

However, the system is flexible enough to provide ratings, not only on a tournament-by-tournament basis, but also round-by-round, session-by-session and even frame-by-frame basis!  Indeed, for the major tournaments (namely the World Championship and the UK Championship) the ratings are usually updated on a round-by-round basis.

 

End of Season Awards

At the end of the season, the Professional Snooker ELO Ratings produce 2 awards for the season.

 

The first award is the "Golden Cue" – which goes to the player who has the highest rating at the end of the season, after the World Championship.

 

The second award is the "Player of the Season" which goes to the player who has made the best progress up the ratings over the course of the season.  In the Professional Snooker ELO Ratings, this is not simply the player who has risen the most places, or the player who has earned the most rating points, but a calculation is performed in order to account for the fact that it becomes progressively harder to earn more points the higher a player's rating is.

 

To see who has won what award in the past, visit the awards page.