How does MMR work

Does match making try to make every game fair, AKA 50/50, or does it try to “place you where you belong”? I’ve heard both schools of thought, but I’d lile an official response.

I go 50/50 no matter my rank, been between 1500 and 2600 for 3 years now. Once in a while I’ll shoot up or down, but usually 50/50. If i can go 50/50 for a wwhile at 1800 and 50/50 for a while at 2400, then 50/50 at 1800 again, something is wrong.

It’s basically a statistical 50/50 based off everyone’s winrates and minor stats. It doesn’t keep you down because the way to break the statistic is to have better team coordination. The matchmaker doesn’t know how good everyone is at teamwork, so by learning how to do that effectively you can climb easily.

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Being at 50/50 means you’re at your rank. So, to answer your question, both.

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OP mentions a range where he was able to stay 50/50, personally i believe that people’s SR is basically in a range of + or - 500 SR from where they are at any given time. (this doesn’t apply as well to higher ranks because the brackets get narrower {like at 4k id say the range is within 100 sr})

Both and neither. Briefly, the matchmaker only makes the game if it is predicted to be close to 50/50. It then raises the MMR of the winners, and lowers the MMR of the losers, and uses that new data to make a better prediction in future games. If a player is misplaced, they will win more than they lose (or vice versa), because the 50/50 prediction was wrong in their case and their MMR will rise over many games played, until they find their correct level (where they belong).

See How Competitive Skill Rating Works (Season 12) → Summary → “Summarize matchmaking, rating, and progression for me” for details. The references are mostly Blizzard statements, if you’d like official commentary on the topic.