Terrible Teammates

Hey, recently I've been getting matched with absolutely horrid teammates. I was doing really well for a while, and was on a 7 game win streak with a pretty good match history record. Now my teammates are some of the worst players I've seen (and I've played on a friend's level 5 account for about 5 games) and it is absolutely terrible. Normally I can do well to carry, but every time they stole every kill and then did absolutely nothing with that kill. People were arguing 24/7, ADC's don't know how to kite, supports that never buy a sightstone, top laners that don't know how to push a Nasus away from farm... is it because I was doing moderately well? Currently my match history is absolutely terrible because all of a sudden I've been matched with the worst of the worst. Can anyone relate?