Can someone explain?

Can someone explain why this games matchmaking seems to follow a certain pattern? It seems like series of 5-6 games where enemy team is obviously less skilled and your team just facerolls. Then after that there will be 5-6 games in a row where your teammates are quite clearly less skilled than your opponents, including yourself often. There never seems to be an even spread. Ever since I started using lolwiz I'll notice that I have a few games in a row of higher quality with plat and some dia players. Then suddenly trough into silver and golds only for a few in a row (this is after winning several games in a row which should mean that I queue with higher and higher rated players subsequently). So my question is, why does this game have such a hard time queuing me with people of equal skill?

I'm obviously not saying that I'm always on either a win streak or a lose streak. Simply saying that it happens so often that it is pretty noticeable, especially after using lolwiz for a month.