A serious issue in ranked

Lately, there's this strange phenomenon happening in my ranked games. I am getting former opponents as allies, and former allies as opponents.

Just take today. Duo'ing with a friend of mine, I somehow got the worst possible team in my division (I was jungle Ammumu and really couldn't do much). Anyways, everyone fed their lane as hard as they could, especially a Draven on our team, who my friend was certain was "trolling". Needless to say, we lost and I moved to the next one without my friend.

Strangely enough, I met the same draven except he was now on the enemy team! Since he somehow felt responsible for the loss, he wanted "to make it up to me" by tilting his team on purpose! Since it didn't affect me directly, I wasn't as upset but just imagine if it went the other way around!

And no, this wasn't the first time it happened. I recall a similar incident less than a week ago.

I mean, if this was normals, I would completely understand but in ranked this is pretty messed up.