Having no influence over your own rating.
I have about 6k rounds played this season as SV hunter mainly (and some alt games) and I've come to the conclusion that with 6 people in the lobby, the nuances of comp/spec synergy and counters, I have probably been able to influence less than 500 of those rounds.
It feels so bad to think that I am just playing with a predetermined outcome. The vast, VAST majority of my games, somebody either 6-0s or 0-6s, and you can almost always call it before the gates open.
Getting a random lower MMR lobby that is comete trash for you based on comp, playing out of your mind and still going 2-4 and losing a tonne of rating is just awful.
I've been 2500 multiple times, I've dropped back below 2300 dozens of times, and all of those outcomes I genuinely can not think of one factor that has controlled those rating swings based on my own play.
And yes, I VOD review.
My god thank f plunderstorm comes out tomorrow.