yes... yes it is ... but at the same time it is not... according to many much more smart people than me, the game is designed to give a 50/50 win/loss rate....
so if u exceed that you deserve to be a higher rank... yaaaa!!!
if you fail, you deserve to be at ur rank or fall below it... oh noes.....
so... when you play 1000 games, 500 should be wins, 500 losses...
if you are on a streak of wins... say 20 more than you should be to remain 50/50 ratio then the computer match making system will begine to place you with less able people... on losing streaks....
and the other team with higher ranked people, on winning streaks... so on... to equal ur games again...
search both the boards and the forums and you will find amazing amts of info about this vry topic as well as an amazing about of dross... also reddit... riot loves reddit....