Question on How the Matchmaking works

I have been having bad luck as I personally call it where sometimes the match making gives you a certain type of players. I think of it as, once in a while, rito places you people of lower elo compared to the enemy team, with expectations of it being "even". I've been keeping track of all my team's ranks and stats, and so far, I've always had an unranked, duo's with one in much lower elo compared to the other and so on. What I want to know, does this happen to anyone else, has anyone else seen this pattern, like I know my skill level in situations and when I'm simply on tilt. Though these are not seeming like "even" match ups one bit, a simple reply of whether its just my tilt and lack of skill or its an actual pattern and happens to people. Thanks for reading my post :)