How does the game pick your random teammates when you queue?

I'm a diamond and I get master/pred lobbies in pubs so that's fun :D

But same thing applies to my teammates. My teammates are always max the same skill level as I am but I'm still fighting against pre-made pred/master squads every game. That's the reason I play mostly ranked because at least in there the matchmaking is most of the time good.

So if you want to play more relaxed games you need to play ranked in Diamond level at least. This game's matchmaking is easily the worst in any online game I've ever played. Absolutely useless.