**I believe that the system is putting players together who have a larger skill gap than normal, thus leading to really bad matchups where one or two players are completely out of their league. **
I believe this because as a high gold / low platinum player, I go from seeing Silvers to Diamonds regularly (feels like every other game!) - This has never happened in previous seasons, you can just feel how different the matching is lately.
As to why? Perhaps testing? perhaps a side effect of the new queue modes? I have no idea. I very much dislike it because my games are now almost always blowouts - whoever has a the better skilled players wins in a landslide without much room for error - these games are boring, I like being challenged. And if I am on the losing side, it's even less fun, because after your silver teammate feeds the diamond 8 times, you know the game is over.
EDIT
I also think this is a viable strategy to combat boosting. Maybe rito is testing something out. Definitely feels different, though.