Every ranked Dota 2 player knows that more wins equals more MMR, but that hardly tells the full story. In Dota 2, MMR is calculated based on a variety of factors.
MMR calculation happens every season, but after a player has already been calculated once their MMR will always be a reflection of that. So if in the past you were ranked at Divine but then lose all 10 placements, you won't suddenly drop to Herald, instead the game will take into consideration your previous peak skill and adjust based on that.
After placement, the MMR change in a given match is pretty easy to figure out. The game will add up the separate MMR totals from each team and place a "bet" on which team is more likely to win. If that team wins, they get less MMR, and if the other team wins they will get more MMR because game predicted they would lose.
To sum it up, MMR gain and loss is weighted more heavily the less matches a player has. Invisible MMR factors into initial ranked placement, but not after, as MMR gain and loss after a ranked match solely depends on the average MMR of the match.
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