How Does Matchmaking Even Work? If It Does Work...

I am NOT here to complain about other people sucking. I am NOT here to brag about how much better I am. I am NOT here to complain about the game, and how other games are better.

So please, don't comment the usual bullshit hypocritical, overly-critical, and high-horse style stuff.

But what I am here for is to understand how match making works? I just got out of a ranked game, and feel free to look at my last game. Nearly every team mate I had plays the game every day, several games a day, and a couple of them even main the champion they played as. I on the other hand don't play this game very much (more so because I don't have much time), recently I've forced myself to because of the VS event and am looking to get the border. Other than that, I do casual games every now and then with a couple friends. I try ranked out again today just for a bit of fun, and I outperform everyone on my team.

This is also not the first time I've noticed this. I've went months without playing the game and coming back just to check out the features that are new and what not, and same results. Is this match making at an error, is this my brain only picking up the poor games over the good ones (even though most games I play with friends), or is this just due to MMR, and some factor there I am not understanding.

I just want to understand so I don't need to get annoyed or frustrated anymore. Because in my head, someone playing every day, many games a day, should be doing much better than me, who plays minimal. And if they main that champion, even more so.

Would love some insight, and again I don't care who is better or who sucks, I want to understand the matching of players, because from who I got matched with last game, ASIDE FROM STATS, the attitudes in the game and some decisions they made did not line up with me at all.