While you’re in queue, League’s matchmaking system puts together a game that tries to balance three things:
- Fair matches - Each team is roughly the same skill
- Position preference - You get to play a position you want to play
- Fast queue times - The time spent queuing is as short as possible
Trying to keep these things balanced requires a lot of tuning, but here’s a rough guide on how it works behind the scenes.
Your Matchmaking Rating (MMR) is a number that Riot uses to determine your skill, and when matchmaking, the skill of your opponents. Everyone’s MMR starts at the same point when playing a queue for the first time. It goes up when you win, and goes down when you lose. When looking for games to put you in, it will look for other players whose numbers are close to yours. You have a separate MMR in each queue, so you can climb in one queue without it affecting others.
To the matchmaker, a “fair” match can be loosely defined as a match in which each team has a 50% +/-1% chance of winning. In a perfect match, ten individuals with identical MMRs queue at the same time, each having selected a unique position that they’re well-suited for. That situation is incredibly rare depending on who is queueing at the time, so sometimes teams can have very slight skill differences (on average, no more than 4-5 MMR).
You must select two preferred positions when entering a draft queue. Your Primary position will be prioritised, with your Secondary as backup. In the event we can’t find a full team comp at your skill level, there’s a small chance you will be Autofilled (which we talk about in-depth here). It’ll trigger if queue times get too long, which is usually because there’s a shortage of one or more positions in the queue - we consider this a last resort to get you into a game.
Fast queue times
Having fair matches is still a huge priority to ensure League is competitive, but long queue times can be frustrating. Ultimately, we’d rather you wait a little longer in the queue to get a fairer match, but we know waiting in a queue is probably the least fun part of League. The longer you’re waiting, the matchmaking system may be searching slightly further from your MMR.
Bringing it all together
As mentioned, the ideal scenario is that ten individuals quickly play a perfectly-balanced match. But there are plenty of factors that we also have to consider:
- Matches played during low-activity times of day
- Parties of players with very different MMRs
- A shortage of one or more positions (sometimes resulting in one or more players being autofilled)
These all throw curveballs at the matchmaker, forcing it to weigh one aspect more heavily than the others. There are also factors that affect the perception of a fair match:
- One or more players trying an off-position
- One or more players trying an unfamiliar champion
- An otherwise fair match in which one lane has an unfair matchup
- Games can snowball out of control with early game champions or assassins, for example
- Sometimes, players just have bad games!
Climbing the ladder
While MMR is the number we use to determine your opponents, your personal progress is represented by the Leagues system. Here are a few familiar situations to illustrate the difference between your League and your MMR:
- You’re winning a lot, and the matchmaker is placing you against stronger opponents.
- A Silver player pushing for Gold should expect to see higher-tier players in their games. It means you’re winning more than you’re losing, and it means the matchmaker is starting to suspect that you’re worthy of higher placement. If you’re on a big win streak, you may even start to see opponents several divisions above you.
- Your opponent is losing a lot, and the matchmaker is placing them against lower-ranked opponents to find them an appropriate spot on the ladder.
- The team’s average MMR is the same, but one team has five roughly-equal teammates and the other team has a few very highly-ranked players and a few lower ones. This one is pretty rare outside of full-premade teams, but we make our best efforts to try and ensure that we still balance queue times into fair matches.
While we know some matches may feel like stomps, we do try to make sure all teams have a 50 +/-1% chance of victory using all the information we have, because part of what makes League so competitive is getting to face similarly-skilled opponents.