Matchmaking.
Since I hit level 18 I experience worst games. For some reason, im put nearly always with people that have far better skill than me, a lot of times even with people in ranked. Last time I played against two gold and had a silver in my team. I have no idea how im to compete with them, since not only they are more skilled, they have access to better masteries, more runes etc.
I don't mind losing, that's not what bugs me, Im just sad that i cant have (in my opinion) fair competition and im uncomfortable with the reaction of my team when they see my level of skill and when I see they understanding when they found out im from different level/rank.
(maybe im just noob and I should go play Minecraft, but until now it was ok)