Why am I seeing unranked players in my game?

I've been going up and down between Silver 1 and 2 for a while and noticed that I ran into so many unranked players that has made the game hard to enjoy. I remember reading somewhere that players who just made it to level 30 have the skill levels equivalent of those in Silver III elo. I think this is just ridiculous considering 90% of the time, if the game is either terribly in or against my favor, it is because an unranked player in our/enemy team is feeding.

I just played with a Katarina mid in my team who was at one point 4 levels behind in her lane opponent. Although the lane opponent was a heimerdinger, if the Katarina sat under the turret and tried to pick up some farm with her Q, she wouldn't have been that behind. She also had terrible pathing that allowed so many opportunities for the enemy thresh to hook her, and everything about the way she played did not demonstrate the skill levels of the players in Silver 3.

This formula you guys came up with of placing players of low level in higher elo than they belong in is what's causing this "stomp or be stomped" games that is mentioned in this forum. Before even taking a look at champion balance, you need to look at player balance and come up with different ways to determine in which elo a player might belong in.