Ok, you can say it's just 1 game, it's flex queue or whatever but i have experienced this even in solo queue.
Lately most of my games are a one side stomp and it's pushing me away from ranked queue. I would never have expected to see me playing aram because i literally hate that game mode but i'm actually enjoying it more than summoner's rift right now.
I hope this get fixed soon because it's not fun to wait for 20:00 and either surrender or watch the enemy team surrender because the gap is just so big there is no chance of comeback.
I'm not saying every game is like this, but maybe 80% of them.
EDIT: since people seem to be convinced this is just a one game i'll post the screen of my last games too.
If you add the one above these are 4 of my last 5 games.