I feel the game itself is fairly balanced, but....
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1719824169/220762443?tab=overview
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1719829607/220762443?tab=overview
I know this is gonna get the typical crying that comes from lol users about how its all my fault and i could have done better to win, yada yada.
these are the first two games of the season on my shitty plat smurf account. i had a similar effect on my main account as well.
Moral of the story, is it doesn't matter how good you are, the matchmaking system in league of legends is just terrible, its based on win/loss