Placement matches

I am trying to do my placement matches on a fresh account. My other account is mid silver. However, I've been playing with people in low gold to high silver. However, I don't understand how riot calculates placement matches, and how they affect your overall ranking. I have played 4/10 of my placements so far and lost them all. The game i just came out of included a 0/9 Allistar top and a 3/10 varus mid (which he distinctly asked us whether we minded if he went mid). I played as Leona and scored an average 6/5/13. As an unranked, why doing better than these Golds i am placed with. Will I end up getting bronze 5 simply because I get placed with people who cannot play the game. Not one of my matches has been close, why can't i be on the other team?