The ranking system ranks is determined by matches played in that week, so if you have a better win/loss ratio then another player overall and they have won more matches than you in that week then they will be ahead of you in the weekly ranking system, someone correct me if i'm wrong.
The weekly ranking system is determined by matched played only in that week
if you read what i said, ive played about 400 matches THIS WEEK since the reset. and im seeing people ahead of me that have barely played 100 matches total. and as i said we know what kinda player i am. i win like 85% of my matches