Weve previously talked about how the average team MMR is the way Riot matches players against each other and determines LP gains. Consequently, if you duo queue with a player that has a higher ranked MMR than you, youll increase your average team MMR and the amount of LP you win as a result.

What factors into MMR?

Amount of MMR gain or lose depends on the two main factors:Average Match Making Rating of all players you faced in the normal or ranked game.If you are having a win or lose streak because MMR is much more sensitive than league system. You can have Platinum 3 MMR but Gold 4 league due to huge winstreak.Nov 12, 2017

Does pre season MMR matter?

Any MMR gains you get during the preseason are halved just a few months later. LP gains and losses matter even less, because when the new season starts your initial placements will only be based off your MMR from last season, not your ending LP.