Editing Matchmaking (section)

=== 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.<ref name="S5CPBlog"/><ref name="MMBlog2"/>

There are three main factors that determine how much the player's MMR changes:<ref name="S5CPBlog"/>

# What is your skill rating compared to your opponents’ rating?
# How new are you to ''Overwatch''?
# 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.<ref name="S5CPBlog"/> In Competitive Play, these adjustments are shown in the Rank Progression screen with ''Consolation'', ''Reversal'', ''Uphill Battle'' and ''Expected'' [[Competitive Play#Rank updates|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 Play|Competitive]] rating change frequently and/or dramatically.<ref name="S5CPBlog"/>

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.<ref name="S5CPBlog"/><ref name="MaddrenTweet">{{cite web|url=https://twitter.com/SrslyPaladin/status/1655704344527003648?s=20|title=Tweet chain by server engineer, Morgan Maddren |author=Morgan Maddren [@SrslyPaladin]|quote=The highlight of the S4 midcycle patch for matchmaking is a pretty substantial rework of our MMR decay system. Since...|date=2023-05-09 |accessdate=2023-06-23}}</ref> 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.<ref name="S5CPBlog"/> In Competitive Play, adjustments caused by rank uncertainty are shown with the ''Calibration'' rank modifier.