Quick question about Provisionals

I just started playing Ranked and i am on my 6th game of provisional's, every game so far the enemy team has usually been comprised of a plat 5, a few golds and Silver 1's. But however my team, have been made of Silver 1,3s and 4s. My question is, how does matchmaking work and does it not favour players in their provisionals? Also, is ranking based off wins or performance per game, because in most cases it has been a loss but I am always positive (17-10-12~)