Matchmaking Rating, or MMR is a value that determines the skill level of each player.This value is used in matchmaking. Winning increases a player's MMR, while losing decreases it. Players with the highest ratings are listed on the world Leaderboards.n general, parties receive bonus MMR when searching for matches. This is meant to compensate for superior party coordination, as well as partying with highly skilled members. 1  Parties' skill and experience values are counted as an aggregate, not individual for each player. 2  Parties will receive a higher adjusted MMR.