your win ratio is the exact percentage of matches you've won based from your QI amount (QI is games played)
If you've only played say 100 games but you've lost 50 of them, then your win ratio would be 50%
If you've played say 11,895 games like i have, my win ratio is 57% meaning i've won about 6780 games, and lost 5115.
Hope this gives you a better understanding of how it works, the more games you play over time the harder it will become to raise or lower your win ratio.