How does matchmaking work?

I'm gonna get called on this

"it's cognitive bias" "it's not true" "you're just not good as you think you are"

I've had a massive stretch of games since I dropped from gold a short while ago where pretty much the majority of my games are filled with complete crap on my team....I'm talking at least 2 positions feeding like it's their job, if not all of them. It's gotten to the point where I either carry hard (as in four of these heavy *** on my back or we lose).

I've played a decent amount of mobas over the years. I'm not pro but I've got great game sense. I can read and adapt to the state of the game. It's my strength. These games are as close to unwinnable as they can possibly get. And i mean to the point where I need to carry so hard because my teams attempting to snatch defeat from the jaws of victory. It's gotten to the point where my friend (a higher elo than me from our dota 2 days) who's the quickest to shred me to bits just to troll has admitted that these games are ridiculous.

Basically I know this is going to get buried as another "elo hell" post but I gotta vent somewhere and maybe ask? How the hell is matchmaking working because I am guaranteeing the other team is the majority of the time a better balanced one (score is spread across the team rather than one dominating).