Can someone explain?

Hello summoners.

Not trying to QQ so forgive me if it comes off that way but I'm just trying to understand how matchmaking works.

I'm currently unranked and have virtually no interest in playing ranked. Right around the end of the season I started being matched against high silvers, golds and plats. Even a few diamonds. Needless to say It isnt very fun to play against players who outclass me significantly.

So my question is, how does matchmaking work for normals? is there any kind of mmr thats account for? why dont ranked people playing normals get matched with other people in their bracket instead of unranked people? is it just because the season is over?

Thanks in advance!