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Matchmaking Rating (also known as "MMR") is a behind-the-scenes number calculated for each player to match them with players of similar skill. In order for the matchmaker to place similarly skilled players together, it assigns everyone a matchmaking rating that indicates how skilled the system thinks the player is. The players Matchmaking Rating is only used for matchmaking. Your rank is supposed to express your MMR, but it moves faster after wins and losses. After a game you receive Personal Rank Adjustments (PRA) and the Performance Adjustment (PA).
The intent behind MMR is to match players by skill. This is accomplished by comparing an assigned number (MMR) that adjusts based on the relative MMR of the opponents players win or lose to. Matching players by their effectiveness or performance helps make sure that less experienced players aren't always getting stomped by expert players, and that competitors at all levels are earning their victories by battling players of roughly equivalent ability.
Unranked Draft Mode and Hero League use a player's Quick Match MMR as a guideline for players first entering these queues. Similarly, Team League uses an average of all players' Hero League MMRs as a guideline to determine how new teams will be matched. After Season One, the system will use Unranked Draft instead of Quick Match MMR as the guideline to determine a player's initial Hero League matches.
Calculating the MMR[edit | edit source]
An individual player's Matchmaking Rating (MMR) is primarily determined by the amount of games that player wins versus how many the player loses. When you win a game, your MMR goes up, while the opposite is true for when you lose. If your team won the game, but you performed poorly you would receive negative Personal Rank Adjustments (PRA) points, but you would still gain MMR. If on the other hand your team lost the game, but you performed very well you would receive a positive PA, but you would still lose MMR overal. Therefore winning or losing a game is the most important factor of the system.
The system can then use an individual player’s performance to adjust how much MMR the player gains, or loses, for a game. If they’re performing beyond expectations for their current MMR, the system will grant more MMR when they win, subtract less when they lose, and they’ll more quickly arrive at the proper MMR for their skill. The opposite is also true if they’re not performing up to expectations.
The algorithm that determines your performance uses 20 different factors, among them siege damage, hero damage, KDA, EXP soakes, CC time but also many others that are not publicly known. Those factors are used to tell how a particular player in a particular situation is doing. To rate your performance, the system applies context to these stats by looking at the Hero you’re playing, the Battleground you’re on, the game mode, and what region you’re playing in so it can make fair comparisons against other similarly skilled players under the same conditions. At the end of the process you receive a number between 0 and 1 that rates your performance, 0.5 representing a completely average game that would result in 0 PA points. Depending on what that number is you will now gain or lose a maximum +/- 50 PA points based on your performance.
By looking at these stats across the entire player base, the system can see which stats are most important for effective play and create a data-driven model of what the most highly-skilled players are doing in any given situation. What differentiates a highly skilled player on a given Hero isn’t always obvious, though. For example:
- When looking at a Hero like Illidan, it’s pretty straight forward. A good Illidan does a fair amount of damage, soaks a lot of experience, doesn’t die very often, and captures a lot of Mercenary camps. Illidan has a fairly high skill ceiling, though, so we expect there to be a sizeable difference in all of those stats between a highly-skilled Illidan and an average one.
- However, for a hero like Kerrigan, the difference in raw stats like damage and experience between a high skill and average skill player isn’t quite as dramatic. Instead, the biggest thing that sets apart a highly skilled Kerrigan is how effective they are in landing crowd control effects, so the system would put a larger emphasis on this stat for Kerrigan players. She’s still being evaluated on all the same stats as every other hero, though, so a Kerrigan who spends the game only attempting to land stuns would not necessarily gain the same amount of MMR, as they would need to also contribute to the game in a meaningful way on top of landing lots of CC.
Other Notes[edit | edit source]
- The system doesn’t have any preconceptions about which stats are important. Instead, it is measuring how players are playing in particular situations in order to determine which stats are most important to highly skilled play.
- The performance-based aspect of the system will be disabled initially when a new hero launches or after a hero receives a major rework to allow the system to gather the data it needs to make performance comparisons. During this period, the system will effectively work like it used to with MMR adjustment based on win or loss.
- If you're focusing on just 1 stat at the expenses of the other 19 stats, your overall performance will suffer. The system cannot be fooled to believe that you should be accelerated faster through the ranks when for example, you're trying to collect CC time as Kerrigan or Muradin.
- Players need to realize that by not doing anything (sitting at the Altar) when a game is about to be lost will hurt them even more, because they will lose more points.
- While inside vehicles (Dragon Knight, Garden Terror), your stats will go up really fast, but it's important to mention that the matchmaking compares your game to millions of other games on the same map and again, you sacrifice other stats in favor of the ones you gain in vehicles, so it's the same boucing act that balances itself out over time.
- Game duration does't have any impact on the system, prolonging the game won't have any effect.
- Even a full death in the last minutes would really only be a minor modifier overall once diluted against your overall performance in the game. The biggest factor for MMR adjustment is still whether you won or lost. Your overall performance is secondary to that and any particular moment is just a small part of that overall performance.
- For new heroes or major reworks, the performance-based adjustments will basically be disabled until enough data exists.
Matchmaking in Quick Match[edit | edit source]
The main purpose of Quick Match is that you have a guaranteed character selection, and matches that start as soon as possible. Quick Match Matchmaking will do its best to make a good game using a large number of factors but while archetypes may be even, certain hero combinations may end up having an advantage/disadvantage that are partially related to whatever combination you may have done with your group, at what time you are playing or even in what region. If you are in the mood to win with a "real" composition on a map, Unranked Draft or Ranked Draft might be better.
Regardless of the above, there are some guidelines for the Team and Hero Composition during Matchmaking. See: Matchmaking in Quick Match