Yesterday, Dean Ayala responded to a Tweet, explaining how exactly matchmaking works in Arena. While players have (obviously) knew that it’s based on the record, we never really had official confirmation on how the system works EXACTLY and whether some kind of MMR is involved. Some have speculated that instead of just matching based on the score, skill level was also taken into account.
As it turns out, each Arena record (all the way from 0-2 to 11-0) got assigned a specific value, which increases the “better” the record is. Order and distance between each record, so which one is actually better and by how much, is quite complex. Just like with other game modes, the game will try to find people with a similar value – so first and foremost the exact same record you have (e.g. if you have 3-1, Arena will try to find another person with 3-1). But if no one with the same record queues, the algorithm will slowly expand the search, touching other record. And so, a player with 3-1 record might then expand into the 4-2, or 3-2, or 2-2, or maybe 2-1 territory – we don’t know the exact numbers, of course, but the point is that it will then look for “closest” value.
Arena does NOT match based on skill / MMR – e.g. if you win a lot at Arena, you don’t get stronger opponents when matchmaking. However, “skill level” is also tracked by the devs – this is how they know that, as it turns out, Arena matches are usually decided by skill. It means that if you match a worse player and a better player, the better player is much more likely to win (I know, it might sound obvious, but it’s quite common to believe that e.g. the deck you drafted might play a much bigger role than your skill).
All records (0-2 –> 11-0) are assigned a value and are then matchmade by that value. This isn’t exactly correct, but it looks something like this:
0-2 = -10
1-2 = -9
0-1 = -8
etc
etcThe order of records and distance between records is some complex table. Basically we have enough data at this point to understand how well a 2-0 performs vs a 2-1 or an 8-2 performs vs a 0-0 on average.
And just like other matchmade modes, the matchmaker looks for an opponent with an identical value, then after X time extends the search parameters a small amount and repeats that process until a match is found.
Contrary to popular belief, match outcomes are decided almost entirely by the skill level of the players involved. We know this because we track a skill rating as well we just don’t use it for anything outside of data tracking.
