I have layed a few games with a friend of mine who is a herald (3-5). We were getting players of mixed skills. Now every game I queue, it is an absolute stomp. And not regular stomp you encounter everyday. It is absolutely unwinnable game where we lose atleast 2 (mostly 3) lanes and one of the enemy plays like a god. We are not even that different in rank, I was an early archon, and neither he nor I have ever abused rank. Everyone here is absolutely sure that the ranking works perfectly. How does it work for you guys? Do I apologise to gaben for queuing with my friend? Have any of you experienced this? I am not talking about isolated games, it is ongoing for 10+ games.
Something similar happened to me after playing with a herald friend. Not sure if it was a coincidence or been flagged for something but i was having terrible games with toxic teammates and was not winning our lanes in most of the matches. Lost around 250MMR but I recovered my MMR with recalibration. In fact gained over 400 till now. Matches seem to be normal as well.
Try recalibration if you can. In case you are flagged for something this should help