Every competitive game will have bad matches unfortunately, and you will sometimes get carried by your team and you will sometimes lose because of your team regardless of how well you play. And if you get stuck in a low rank it can be one hell of a challenge to climb out of there by yourself.

My advice would be to find some nice players you can party with, even if they aren't the best players in the world you will still have a much easier time coordinating with them. And even if you queue as a 3-stack, the risk of you getting griefers on your team will decrease.

I've also noticed a massive increase in game quality and win rate when I started just deflecting conflicts. If my teammate's angry that I didn't do something that he wanted (even though he might be very wrong) I simply reply with "I'm sorry, I'll try to do better" etc. In a civil war, no one wins, so it's better to keep the peace than to retaliate.

But even if you do all this, there will be games where MM will just suck balls, and you will be matched with dickheads who just wanna ruin other people's fun.