How do you improve your MMR?

What do you guys think is better. Having a smaller hero pool and try to one trick or a wider array of heroes. I’ve been trying to “master” them all. Some I can’t do any good with no matter how much a i try but I have improved my pool quite a bit lately (Late night QM isn’t a real good test though)

Also a side note: So today I managed to get quite a few wins after 2 AFK’s in a row which dropped me to Silver 5 but just progressed to Silver 3 with a killer win streak. Then lost a couple of matches (Someone last picked Valeera on tomb and had less damage and kills then me on Johanna) and got negative personal rank adjustment.

To me it feels like it turns out this season it’s trying to pull me down to even lower ranks. Last season at Silver 1 I was getting positive rank adjustment. If feels like the game really wants to make you play smurf accounts. Or maybe I’m just getting worse/angry (wangry?) and time to give up the game. Sorry about the rant!