CoH2 uses an ELO rating system.
http://en.wikipedia.org/wiki/Elo
Long story short. You start with 1000 points as a new player. From there you earn or lose points after each match. The points you earn/lose are weighted by the point difference (rank difference) of the players in each match.
Therefore, it doesnt really matter how many games you play. You only need to consistently win against people with more points to rank up quickly. On the other side, if you play 400 games and lose 50% of them, and assuming equal strength of your opponents you will still stand at the same point where you started at 0 games.