Matchmaking

Matchmaking is a system that automatically assigns players that join a matchmaking queue to matches based on various criteria. Matchmaking is used in all game modes, except Custom games. The primary goal of matchmaking is to create as fair matches as possible.

Factors in matchmaking

As a core, matchmaker is a mathematical formula that takes into account multiple factors, including but not limited to:

• Skill: The matchmaking system will try to group players with and against players of similar skill. The game represents "skill" as a hidden matchmaking rating, or "MMR." In role queues, the matchmaker will prioritize placing pairs of similar MMR players on each role on either team. All game modes, including Competitive, only look at matchmaking rating when creating a match; outward-facing skill tier and division have no effect on matchmaking. However, with the removal of seasonal soft resets in Season 4, the players' rank closely matches their MMR in the vast majority of cases.
• Queue time: The matchmaking system will try to find a fair match in as little time as possible.
• Ping: Players connected to servers that are geographically closer to one another are prioritized in order to minimize lag.
• Group size: The matchmaking system will attempt to find groups of equal sizes to match against each other. For example, if four players are looking for a game together, the matchmaker will try to match them against another group of four.
• Group wideness: In Competitive Play, the matchmaking system will try to find two groups of a similar rank disparity. For example, Gold 3 player grouping with a Grandmaster 4 player will attempt to be matched with another Gold 3 player grouped with a Grandmaster 4 player.
• Avoid priority: The matchmaking system will try not to include avoided players. However, they may be released from the list if the queue times get too long.

Matchmaking rating

In order to assess the fairness of a match, the matchmaker needs a way to approximate the players' skill. Matchmaking rating (MMR) is an internal rating (not visible to players) that is used to estimate the player's skill relative to other players. MMR is separate from SR.

MMR is tracked separately for each role and presumably for each playlist, meaning that the player has a different MMR for Unranked, Competitive and Arcade playlists and each role and queue in them.

Updating MMR

Matchmaking rating updates after every match. MMR is only affected by the result of the game: When the player's team wins, they will gain MMR, and when they lose, they will lose MMR. In-game statistics or post-game accolades have no effect on how much MMR was gained or lost.

There are three main factors that determine how much the player's MMR changes:

1. What is your skill rating compared to your opponents’ rating?
2. How new are you to Overwatch?
3. How frequently do you play that specific mode?

As creating a perfect match is virtually impossible, one team will often end up having slightly higher average MMR than the other, and is assumed to be more likely to win the match. Therefore, if a weaker team manages to win against a stronger team, they will gain slightly more MMR than if the teams were equal. The opposite is also true, meaning that if the stronger team wins, both teams will receive a smaller MMR adjustments, compared to a perfectly equal match. In Competitive Play, these adjustments are shown in the Rank Progression screen with Consolation, Reversal, Uphill Battle and Expected rank modifiers.

If a player is new to the game, the matchmaker is unable to accurately assess their skill level with how little information it has. As such, the player will receive larger MMR adjustments to get them to their correct skill level faster. In most cases, only 5 games are required to get players around their correct rating, but this is still a broad estimation. Therefore, new players may see their Competitive rating change frequently and/or dramatically.

The same also applies to players that have not played for an extended period of time: Each player's MMR slowly decreases and the system's uncertainty of their rating slowly increases while they are away. This amount of uncertainty is generally unnoticeable unless the player has been inactive for an extended period of time. This uncertainty rating allows players to gain and lose MMR more quickly, so when the inactive player returns, they can jump back to their previous rank if they perform well, or they can lose MMR faster if their actual skill has decayed. In both cases, playing more games will increase the certainty of the player's MMR and causes them to be ranked more accurately and receive more stable adjustments. In Competitive Play, adjustments caused by rank uncertainty are shown with the Calibration rank modifier.