MMR (Matchmaking Rating)
The hidden skill rating matchmaking uses, distinct from visible rank.
MMR (matchmaking rating) is the hidden numeric skill estimate the matchmaker uses to pair players of similar strength, which can diverge from a player's visible rank tier — a high-MMR player on a losing streak might still face tougher opponents than their rank number alone suggests. It adjusts based on wins, losses, and reportedly performance within games, though the exact formula isn't public. Players who feel their matches are 'harder than my rank' are often noticing an MMR that's outpaced their displayed tier after a hot streak.