Strangely low score

Question,I play every day, and achieve all the daily challenges.  I may not always advance each week, because some people just grind more than me, but I'm usually within the top 5 or 10.I'm currently in the Gold league this week.So, how is it possible that after completing every single daily challenge this week, and playing many more matches after completing the challenges, that I have half as many points as the person in first place, and am in danger of being demoted to a lower league?  I'm 21st out of 25, and about to go back to the silver league after this week, because I can barely stay out of the bottom.  This is totally unfair!  Does this happen often?