Overwatch – Competitive mode

After some digging I found this on how the MMR is determined and suspect the new skill rating will be along similar lines:

Anyway, this leads me to matchmaking rating. This rating is the most important thing that we try to match on. Basically this rating means “how good are you?” Commonly, you’ll hear this referred to as Matchmaking Rating or MMR. MMR is derived differently in different games. Overwatch borrows a lot of knowledge from other games but also does a lot of things unique to Overwatch. As each player plays games, their matchmaking rating goes up or down depending on if they win or lose. The system is extremely complicated and there is a lot more going on here than I am going to spell out. So please don’t take this as the comprehensive guide to how MMR is calculated in Overwatch. There is definitely a lot more going on under the hood.

In Overwatch, whether your MMR goes up or down is contingent on winning or losing. But there are a number of factors that determine how much that rating goes up or down. For example, what map you’re playing on and whether you were attacking or defending is factored in. We know the win rates on attack/defend on all of the maps and we normalize accordingly. Not all wins and losses are equal. We also look at your individual performance on each of the heroes you played during the match. Everyone has better and worse heroes and we have tons of data showing us what performance levels should be like on those heroes. We also look at your opponents and whether or not their matchmaking rating is higher or lower than yours. These are just a few of the things that are considered when determining how your skill should go up or down. At no point in MMR calculations do we look at your win/loss ratio and win/loss ratio is never used to determine who to match you with or against.