What's the point of 2v2 randoms? If you get afk/droppers/horrible teammates in placement games you're fucked.
Then your ELO is trash and it's a vicious cycle of horrendous experiences.
I don't think this describes how the elo system works. As far as I am aware the elo is linked to the team in these games and even if your elo did drop the matchmaker would then be trying to hook you up with a teammate with higher elo to offset your low score. In any case the pool is probably too small for any of this to matter