How does a match up like this happen?

I understand that players are new. I understand that the prelim phase of ranked play is meant to judge people against a degree of opponents to find their best fit. This is not meant to call out anyone based off of skill or any number of other things. I am just wonder how matchmaking deemed this an acceptable match up?

I just can't get my head around 4 people in prelim matches in the same a game, with 3 on one team. Let alone for a first prelim match, with silver players. We understandably got tossed. It was legitimately agitating and entirely unfair to me almost getting me demoted over a loaded game and incredibly unfair to crush 3 people on their first prelim game basically trying to make them lose or even just not want to play.

The worst part was, I was an ass. I thought these people were legitimate silver, that had no idea what they were doing. I got made, I took it out on my team. Until the Ekko told me he was new. So I looked up the game. Now I just don't know what to do.