Silver vs Platinum on normal matchmakin

Well...im a silver 1 player, and before u guys do, ill say it before...im bad, i know and im doing ranked as much as i can to become better and better, i do wrong and i play wrongly, BUT it is not normal that it is the 4th month in a row since september 2015 that i got only platinum and gold 2-1 vs my team which is a full silver team (premade). It is not funny playing versus guys that knows a lot better how to play this game, they win everytime, even when we got feeded early, just because they know how to play later as a team even when they're not premade guys. It is not funny at all. Im here to ask to u guys why is this possible...or maybe it is just pre-season that makes the matchmaking so bad. ty