Matchmaking bug

For the past few months, I've had a large decline in my ranked wins. Looking through my stats, I've seen that in about 75-80% of those games, I still did at least decent. I consistently have a good to great kda, I have damage on the board, or damage taken depending on my role, and I'm doing my best every time. And yet I'm still consistently losing my games. It's usually due to mid/top feeding or losing, doing generally poorly, and their lanes getting out of hand. For a while, I didn't question it, and I assumed I was just on a losing streak, and that I'd get out of it. However, my last game just threw everything out the window.

I'm silver 2, and somehow, someway, I ended up queing with someone STILL IN PLACEMENTS. COMPLETELY UNRANKED. If she was great at the game and worked her mmr up, that would be understandable, but she had a CLEAR lack of understanding of the game. After the game I looked her up, and it turns out she's lost every game, except one in which she went 0/6 mid. I'm not trying to rag on her or complain about a particular player, I understand that there's a learning curve and we all have to start somewhere. What I have a problem with, is that in a ranked game, I should be placed against people that are the same or similar rank to me. She was not. As a matter of fact, I would not even be able to queue with her had she been someone I had known, because league won't let you queue with someone more than a whole division away from your rank. So how did she end up in my game??? League, I think your matchmaking has a bug, and you need to fix it. You should also give me a loss prevention for that game since I had no chance of winning whatsoever. Thanks for listening, and please fix this issue asap.

The link is to the game's match history, and Morg is the player still in placements.