every sunday I drop a full ranking

I can only play on sundays. Today I have gone

12/4/10 - lose 11/7/15 - lose 4/6/16 - win 4/3/6 - lose 4/7/6 - win 8/8/8 - win

basically I'm either the tank and die a lot but do a lot to make the team work well, or I have to carry but can't because the rest of my team is god awful...