matchmaking for ranked is shit

i have a gold 4 player in my game and a plat 2 player. why? the gold 4 player had gold last season so its not like his MMR was anything spectacular so why?

the plat 2 player was diamond last season. again. why are they in the same game? I just dont understand how this happens. was my queue time just really long so they took some low gold player and threw him in my game? I dont think the plat 2 player with diamond MMR should have been in my game either...

funniest part was, they were not even a duo

I need some people to drop some knowledge to help me out