Need a Rioter to Explain/Defend This Shit

Just finished a game where I had at least two players in placements (three were unranked this season, but one of the unrankeds was silver last season), while enemy team was all already placed in silver. Ok, let's see what happens. Oh, the ADC afk pushed bot lane all f*ing game going 0/14/0 and ended game with less than 100 cs and 1,740 damage on enemy champs AS A FUCKING ADC IN A THIRTY MINUTE GAME. Next lowest damage was 8k+. No, she did not disconnect or afk. Why is this shit allowed in a silver ANY game? This puts bronze to shame. She refused to leash and wasted flash at lvl 1 for no reason (that I could tell). Minions weren't out and she was in bush bot side watching lane.

Just a bad game, right?

Nope. Third ranked in a row lost as an adc. 74cs w/ 11% kp (0/6/2) and before that THIRTY-FUCKING-FIVE CS IN A THIRTY FUCKING MINUTE GAME (0/7/2). AS AN ADC.

What the fk is wrong with your matchmaking to 1. place this player in a silver game and 2. place not one, but TWO people in placements on one team, with the other having a complete silver line-up?

FFS, if this is how shit your matchmaking is, just make everyone plat+ and be done with it.

Edit: added "IN A THIRTY MINUTE GAME"