The issue isn't the number of wins and the number of losses. It's not even whether some teams have more impressive wins than others. The only reason your rating is as low as it is is this loss:
https://www.warlight.net/MultiPlayer?GameID=9702538Losing to a team rated below 1800
kills your rating. Once that loss expires, your rating will probably jump by 100 points.
Your run is very impressive - it's just that losses to bad teams (even wins sometimes) really hurt.
Edited 3/11/2016 02:08:52