Title says it all.
It seems that no matter how well I do and how much I try to help my teammates, I can't win games. I generally play either jungle or top and, since the ranked changes, I'm losing ~70% of my games, before I was winning ~65%.
I'm realistic, so I know I'm not just getting unlucky every time by getting a trash team, but it seems that unless I am overwhelmingly better than the entire opposing team, I won't win regardless of how well I play.
So, for those that seemed to have figured it out, how do you carry a game?