Why is the ranked system broken like this?

This game consistently does this to me, and at this point I need to know if anyone else has this happen to them. I go on a pretty good win streak with consistent play, don't usually carry but I never feed and I consider myself a player that fits well in their league. However, after 6 or 7 wins, I go on a crazy slump, but the difference in teammates I get is astounding. I go from getting people who understand where to be on the map, how to lane properly, to people who roam towards dragon by themselves with an Akali on the other team. And yes, of course, they flame and sometimes afk from bad attitudes. This is a serious problem, and during these losing streaks I get very upset, rightfully so, and I'm looking for anyone out there that gets this, and if it seems like a real problem.