It's something everyone is confused about. We all have our ideas on how it works but I don't think I've seen any official statements on:
Just be clear, no tricks, please explain it.
While you're at it, maybe tell us:
Thanks!
They've made it really clear a lot of times.
You gain MMR by winning a game. You lose MMR by losing a game. If your personal MMR is higher than the average MMR of the 10 players in the game, you will win less MMR/lose more MMR. If your personal MMR is lower than the average MMR of the 10 players in the game, you will win more MMR/lose less MMR.
Matchmaking starts by looking for players very close in MMR, but as the queue goes longer and longer, the boundaries the "acceptable" MMR widen.
The amount of LP you gain/lose is based on your personal MMR compared to the average MMR of the people of your rating. For example, if you are at Plat 3 30 LP, and your MMR is higher than other Plat 3 30 LP players, then you will gain more LP for a win (lose less LP for a loss), and vice versa.
Your rating at the end of the game (A, S, S-, etc.) is based on your performance on that champion in that particular lane (taking into account farm, kda, kill participation, damage dealt, etc.) Farm is by far the most important factor for non supports.
Hope I helped.
Riot has stated that they intent to never reveal how the grading process works, this is to prevent players from gaming the system.
And don't believe people when they tell you that kda and cs is important for high grades, nobody has proved it yet or even shown convincing evidence that it might be possible. While I have seen evidence that kda and cs are not required to get high grades. If high cs was as important as many claim, then it should be fairly trivial to get a S rank in most of our games and proof would be just as trivial to come by. But I have yet to see it. It also sounds like a way too easy thing to game the system with so I really doubt Riot would use it for grading.
ps: for those who gonna hate and say mmr work on win/loose , then explain me how can a loose bring me 125 mmr ? ^^
