About one month ago, I refused to play in ranked games due to the lack of DECENT teammates. I stayed at around 1200 ELO for the longest time. I honestly just played a bunch of ARAMs and Dominions and Normals, avoiding Ranked as much as possible.
I have been fortunate enough to receive a recent grace in the midst of matchmaking. I have somehow managed to reach 1500 ELO (thanks to my friends).
And yes, you are probably thinking: "He is so lucky!" Couldn't agree more my friends. I am good, but I cannot win games on my own.
Summing it up, I just simply do not understand how at one point I can have the most pro teammates I've ever played with, then suddenly playing with people that seem to know nothing about League of Legends.