My Mmr... wtf is wrong with it

Did you rank up really fast? Your MMR is a lot lower than the current rank average, the system is trying to force you out of diamond. If it were me, I'd stop playing (just enough to not get LP decay) till they hand out season rewards to ensure I get all the Diamond benefits lol :3

You basically need to win. With your current mmr you aren't where you're "supposed" to be according to the system. If you win you'll even out and prove you deserve to be where you are, or you can lose and and drop leagues and you'll probably hit your equilibrium point soon where your w/l lp rewards are even.

I have the same problems lol. the way to get out of this since you are in diamond 5 is to trad lp for mmr (that's the way I see it). That means you win 2 game lose 1. This will raise your mmr but you won't get any lp since you'll gain 18 lp but lose around 20 lp. When your mmr will be back to normal you'll start to gain around 16-20 lp a game again just take some time.

Keep winning. lol

Play more. If you win half your games youll end up where you are supposed to be.

Win more