Updated Arena Rating System

Back in 2006 I wrote a post on the Arena Rating System which still gets linked to all over the place. It's been driving me crazy that people might be reading a 2 year old post to get current information about the constantly changing arenas. I finally found the time and sat down and rewrote the post using the most current information I could find. I promise not to make a habit fo reposting.

http://relmstein.blogspot.com/2006/09/arena-rating-system.html

Team Rating
The initial arena system was based on the ELO chess system where teams had a rating that changed depending on the toughness of their opponents. I'll leave the basic explanation of team ratings the same since they haven't changed that much. Team ratings are still primarly how arenas points are rewarded and how team's are matched up against each other. Players who have used holes in the arena system or switched between a lot of different teams will find that their personal rating is used instead of their team rating.

example:
Lets have team A and team B who meet in the arenas. Team B has a moderately higher score then Team A which means their odds of winning are calculated as being higher for the match. This means that Team B's rating will decrease more if they lose and increase less if they win. Team A's rating on the other hand will do the opposite. There is also an arbitrary number in the formula which decides the maximize number of points lost or won for the match. I'm using the number 30 but honestly this number probably changes based on the rating difference between teams.

Team A's Current Score: 1500pt
Team A's Chance of Winning: 1500 / (1500 + 1580) = .48701

Team B's Current Score: 1580pt
Team B's Chance of Winning: 1580 / (1500 + 1580) = .51298

Now Lets say Team A won the battle then
Team A's New Score: 1500 + (30*(1-.48701)) = 1500 + 15.39 = 1516
Team B's New Score: 1580 + (30*(0-.51298)) = 1580 + -15.39 = 1566

Now Lets say Team B won the battle then
Team A's New Score: 1500 + (30*(0-.48701)) = 1500 + -14.61 = 1485
Team B's New Score: 1580 + (30*(1-.51298)) = 1580 + 14.61 = 1595

Personal Rating
Personal Rating works just like a seperate version of the Team Rating for each player who actually participated in the match. Blizzard put Personal Rating requirements on certain rewards because highly rated arena teams were selling spots to people who wanted to quickly gain points. Each player actually has a Personal Rating for each of the arena brackets in the game. Thus a person could have a very high 2v2 personal rating and an average one in the 3v3 and 5v5 brackets. If a player switches teams then their personal rating for that bracket is set back to 1500.

New rules for Season 4 (May 2008) actually use the personal rating for matching and point rewards over the team rating.

- If a character’s personal rating is more than 150 points below the team rating, they will earn points based on their personal rating instead of the team rating.
- If the average personal rating of the players queuing for a game is more than 150 points below the team’s rating, the team will be queued against an opponent matching or similar to the average personal rating.

Awarding Points
Blizzard has an arena calculator on their wowarmory.com website which can be used to tell how many points your team will earn with your current rating. Only teams that have played more then ten games that week will be awarded points. Also only players on that team that have participated in at least 30% of the matches will get points.


Exploits being Addressed in Season 4

Smurfing
Smurfing is the practice of creating smurf teams by taking a well equiped arena player and putting them on a team with a low rating. These players then artificially inflate the rating of the team and then switch back to their main team. They then use certain methods to make sure they play their smurf team which throws the match. The method works especially well in the 3v3 bracket which is easier to control the matching then the 2v2 bracket and doesn't require as many players as the 5v5 bracket. The new changes for awarding points based on personal rating will of course penalize teams that have players that frequently change teams.

Arena Scouting
Also Blizzard is making a change to arena scouting which is commonly used to make sure their opponents are a smurf team instead of a serious challenger. This method is also used in Win Trading where teams make aggreements to lose a match against a certain opponents. In general Arena Scouting is used at low population times when very few teams are in the queue. This allows arena teams to be fairly certain if both their queues pop at the same time that they are going to be matched together. If one team's queue pops before another then they re-queue.

- "If a team does not enter an arena match that is starting they will lose points equal to the amount that would have been deducted if they had played and lost."