Stupid people in your ranked games

How do you guys handle really stupid people in your ranked games? Some games I feel like there's just nothing I can do because my teammates are just awful.

Here are some recent highlights:

• 0/2/0 Heimer top who feeds two kills and afks for the rest of the game. I'm 2/1/1 mid.
• 1/12 Mordekaiser and 1/12 Nami. I'm 2/0/3 mid, ganked bot lane 2-3 times and got kills each time. We lose in a landslide.
• Diamond 4 full AP amumu that power farms the jungle and does nothing the entire game and a sivir who was told to fall back, didn't listen, and died 20 seconds later to an obvious play. Also she was too slow to ever spell shield a single Morgana Q.

All of these players are plat/diamond. I don't understand. I really. Do. Not. Understand. I'm an okay player, but I'm not going to out carry a 10/1 Riven top as Morgana mid. I can't carry a game with an afk either as Malzahar.

People tell me "shit happens". But for me, shit seems to happen in sprees. Like this is three games in a row of just impossible to carry teammates. I don't understand why it happens so many consecutive times.

If anyone would be willing to give me some help/advice I'd appreciate it.

I don't think I even play badly in these games. I went 3/5/4 as Morgana mid in the game where my support and top fed over 30 kills combined. I was 2/0/something early. I don't understand. 3/5/4 is like the worst possible game for me. I don't understand why my teamamtes feed so fucking hard.