Arena MMR and Rating - Huge Bug/Exploit
It is nearing the end of the first week of Season 9 and something disturbing is happening before our eyes... the MMR and Ratings of Arena teams are spiraling out of control.
Why are MMR and Ratings inflating so fast?
Because there is a bug that players are often stumbling into or intentionally exploiting to never lose MMR, causing you to always gain vastly more rating for wins than you can ever lose for a loss.
How does the bug happen?
MMR of a losing team is not lost when a player leaves an Arena before it ends. This is such a common occurrence that players are often stumbling upon it by accident, benefiting from it without even knowing what happened. Other players are aware of the bug and exploiting it with intention.
and for those who care...
What is causing the bug?
I don't have access to the coding so I can't be dead certain, but I have some clues and anecdotal evidence.
First of all, has anyone noticed the new queue system for Arenas? The game 'knows' how many people are in your party, and queues you for the appropriate bracket. The problem with the coding is occurring at the end of Arena games when points, ratings, and MMR gains/losses are calculated... when a player leaves, the game again sees and 'knows' how many people are in the remaining group and the game is applying all personal stats based upon the remaining number.
Example: In a 3v3 game, TeamB is about to lose! One player from TeamB leaves before the game ends. The player who left is not credited for having played a game at all, and loses no personal Rating or MMR. The two remaining players are credited a loss but for the purposes of personal stats are considered by the game to have been in a 2v2 game, therefore also losing no personal Rating or MMR.
Anecdotal evidence: Today I played a 3v3 game. My team killed the opposing Warrior, and so their Paladin left the game. Their Shaman stayed in the game until we killed, which we did and won the game. The two players who stayed and died (Warrior and Shaman) both received 'Just the Two of Us' (2v2 bracket) Achievements for 1750 and 2000 at the same time, even though they had just lost a 3v3 game. The game 'saw' two players in the group and applied their active 3v3 stats to their personal 2v2 ones instead.
So far, that's all I know. Personally I see no good solution besides to first fix the bug in the code, then reset all MMR and Team Ratings.
If you agree, please help keep this thread bumped!