Determining the AFL's best player has always been tricky. Whether it be umpires, coaches, media or fans, judgements about top players have always contained a large slice of opinion.
Now, using the most sophisticated algorithm ever applied to our game, we are assessing every single action of every player, determining the impact of that action, and providing points – either positive or negative – toward that player's rating compared to his peers.
Along with the obvious acts such as goals, marks and disposals, we've included intercepts, spoils, kicking to a contest, smothers, chasing, corralling and many other 'one-percenters' - along with where and when they occurred - to paint a complete picture of ever player's impact on a game.
And the Official AFL Player Ratings are based on a player's past 40 games, which delivers a long-term view of a player's standing within the AFL.
We have also created positional ratings, so that fans can easily determine the best ruckman, small-medium defender, key defender, midfielder, midfielder-forward, small-medium forward and key forward in the game.
In addition, we continue to monitor results, take fan feedback and consult the top experts to ensure Official AFL Player Ratings remain the most accurate statistical view of our game.
How is each player's rating worked out?
Players accrue or lose points every time they are involved in a passage of play. The score awarded to them each time they are in the play is determined by a complex algorithm formulated and refined over a number of years by Champion Data. Players accrue or lose points depending on whether they have a positive or negative impact on a passage of play.
A player's rating is determined by aggregating his points tally based on a rolling window of the previous two seasons. For example, after round six of the 2014 season, a player's rating will be based on matches from round seven of the 2012 season onwards. However, only a player's most recent 40 matches are used in the calculation of his rating. This creates a buffer for players missing matches through injury, suspension, omission or by not being involved in finals. A player's most recent 30 matches are given greater weight in determining his rating. Matches 31 through 40 are progressively reduced in weighting, from 100 per cent down to five per cent for the earliest game in the window.