6 game streak with atleast someone feeding/afking/trolling

It's not match making. It's the fact that which ever team gets the first few kills becomes completely unstoppable. There was one game I played this season where my team invaded and fed an enemy Irelia a triple kills. From that point on, it was impossible to win. She was nothing short of a god. Unkillable while being able to go anywhere on the map and kill anyone she wanted at will. Another example, a few games ago, I had an Ashe that got an early triple kill, and from then on, the enemy team had no chance whatsoever. These are but two extreme examples. Right now, as I'm writing this, I'm in a stomp where we are 11 kills to their 24 and it's completely hopeless. Nothing we can do. The problem is that large leads are too easy to get.