Does Matchmaking Even Work? Seriously.

I am no Diamond player, and I make stupid mistakes, but I am pretty good at the game, better than the average player. So my question is, does matchmaking work? I heard it only works in Ranked, and not in Normal or Team Builder. It's impossible that it works anywhere else other than ranked because every other game I get at least 1-2 people on my team that don't know some of the most basic concepts, or tend to do really bad. Even in Team Builder, where you are allowed to pick YOUR role, and YOUR champion, there shouldn't be an excuse to go 0/10.

So yeah, just curious so I can somewhat rationalize what's happening. Does matchmaking work in Normal and Team Builder, by skill level like it's supposed to?