Beyond All Reason uses the OpenSkill algorithm to match players, and the interface shows two different numbers for your performance. This causes real confusion. Here is what those numbers mean, what mu and sigma actually do, and how your rating changes after every match.
Tags: beyond all reason, BAR rating system, OpenSkill algorithm, BAR matchmaking, mu and sigma BAR, BAR skill rating
If you check your stats after a match, you will see something that looks contradictory. One screen says your skill is 29.39. The match details say your rating is 20.69. Both numbers are correct. They are just showing different parts of the same system.
BAR tracks two values for every player. One represents the system's best guess at your actual skill level. The other represents how confident the system is in that guess. The rating displayed in game combines both values into a single number you can use for matchmaking.
OpenSkill is the algorithm behind BAR matchmaking. It stores two values per player, and understanding both of them clears up most of the confusion around the rating system.
Mu represents your estimated skill level. This is the system's best guess at how good you are. Winning games pushes mu up. Losing pushes it down. The higher your mu, the stronger the system thinks you are. When you see "skill" listed in the interface, this is usually what it is pointing at.
Sigma represents uncertainty about your skill level. A high sigma means the system is not very sure where to place you yet. New players start with high sigma because the matchmaking system has almost no data to work with. As you play more games, sigma shrinks. The system becomes more confident in its assessment of your mu.
The number you see during matchmaking and after games is your match rating. This combines mu and sigma into one practical number. The formula is straightforward: rating equals skill minus uncertainty. Or in OpenSkill terms, rating equals mu minus three times sigma.
Here is why that matters. A new player might have a high mu from winning a few matches, but their sigma is also massive. The rating number accounts for both. It shows a conservative estimate that keeps them from being tossed into far-over-their-head lobbies while the system figures them out.
Conversely, a player returning from a long break might have low rating that climbs quickly. Their mu might still remember they are decent, but the high sigma from inactivity pulls their visible rating down. As they play, sigma shrinks and the rating bounces back toward where it belongs.
Several factors influence how much your rating moves up or down after a single match:
New players should expect rating swings of 50 to 100 points or more per game in their first dozen matches. This is normal and intentional. The system is trying to find your level quickly.
Players often feel their rating does not match their actual skill at some point. There are explainable reasons for this feeling.
Recent return from inactivity. Sigma rises when you take time off the game. Your visible rating drops below your actual capability until you play enough games for sigma to compress again. The system becomes deliberately cautious with stale accounts.
Catching a hot streak. Three or four wins in a row can inflate mu faster than sigma can shrink to compensate. Your rating jumps, and the next opponents are noticeably stronger. This corrects itself over time as sigma settles.
Playing new game modes. Some game modes or faction choices produce different results. If you only play one faction and switch to another on a fresh ladder track, you effectively start climbing again from a high-sigma state.
The rating system is designed to find true skill, not to judge you as a player. A temporary mismatch between your rating and your ability is part of how the algorithm works through uncertainty.
Understanding the system helps you make better decisions about how to approach ranked play.
Play consistently. Frequent matches keep sigma low and make your rating stable. Sporadic play means high sigma and volatile swings. If you want a rating that actually reflects your skill, play regularly.
Do not obsess over single matches. With high sigma, a single loss moves your number a lot. Over twenty matches, individual results matter much less. The trend line is what counts.
Focus on improvement, not the number. Your rating will climb as you play better. Working on economy management, map awareness, and unit composition drives real progress. Watching your rating obsessively between games does not.
Review games that went poorly. The biggest leaps in rating usually come after a player identifies one specific habit that was costing them games and fixes it. Economy stalls, forgotten scouting, or bad build orders are common culprits.
Rating anxiety is real in competitive gaming. A lot of players put too much pressure on a single number and end up tilting through games that should be fun. Creed of Champions exists because we believe you can play competitively while keeping the environment respectful and actually enjoyable. Win with skill, teamwork, and respect. That means playing to improve, not playing to panic about rankings. If that sounds like your kind of community, we would love to have you.
[Crd] One of the few places where you can for sure coordinate with people in matches with a good supportive attitude. Everybody tends to be understanding and constructive.