Riot answer me that:
**_LP is used to track progression through a particular division as well as determine qualification for advancement. However, hidden matchmaking rating (MMR) is the variable used to determine placement for a division/tier as well as how much LP will be gained or lost in a ranked game.
If your MMR is significantly lower than where the system believes you should be for the division you are in, then your LP gains will be reduced. Furthermore, the amount of LP you earn will not increase until your MMR is raised to a point where the system believes you should be for that particular division. On the opposite end of this situation, you may experience large LP losses due to the fact that the system believes you should be in a lower Division based on your current MMR. Please keep in mind that as long as you continue to win more than you lose, your League Point gain will even out and you’ll continue to make progress towards the next advancement series.
I hope this explanation has helped. You can also check out our Ranked Play FAQ here:
https://support.riotgames.com/hc/en-us/articles/204010760-Ranked-Play-FAQ_**
I think this is unfair!