Znail, on 09 July 2013 - 11:33 AM, said:
The big question is what they did? Did they introduce a decay over time/matches played? Only counting the last 100 games? Or did they simply multiple everyones Elo with whatever constant needed to get the graph they wanted? If it's a one time thing like the last, then I would expect the graph to recover in time.
What they did was this:
1. They discovered that the way they were assigning Elo to players was wrong. A strong player defeating a weak player should get a tiny Elo boost. He was getting a big Elo boost. A weak player wining from a strong player should get big boost. He was getting a tiny one. This results in the red graph where a significant amount of the players are humping the maximum Elo barrier. In a well calibrated system this shouldn't happen so easily.
The mistake they made was a programming mistake. A very understandable one too. I made my own implementation of an Elo ranking system to understand how it works and I made exactly the same mistake. The explanation is rather technical though so I'll skip that.
2. After they fixed the mistake they took the match history of all players and fed that through the algorithm. They basically recalculated Elo for every match that was played. That's how they arrived at the blue graph. The blue graph will not ever look like the red graph again. If it does that means something is broken.
.
Rather it should start looking like this graph:
http://lolmatches.com/charts
Big buldge around 1300 (most players are average!), then a long tail into 2600. The game is only beginning to show that just now.
Znail, on 09 July 2013 - 11:33 AM, said:
The less then 50 matches player group is still a large group of players and they have played enough matches to spread out some in Elo, and should thus also have played enough matches to impact the veteran players Elo. The way the curve looks is not natural and some heavy manipulation of the data most have been done to go from the red graph to the the blue on.
At the time new players started with 1300 Elo. The peak of the light blue lies at and 1250 the rest of the bulk is even lower. As you can lose 25 points for losing an equal game, that means a good number of new players players have played and lost at least two matches or more. This is to be expected really, they're new players.
Edited by Hauser, 09 July 2013 - 05:13 PM.