Merry Christmas to me save these things up for awhile, used 22 today 0 purple. Think maybe you need to increase the % good grief man. 

I have tried opening a couple a day when I had that many and switched to the uncommon ones as well and opened the higher ones when I have a long streak of grade 1 champions. Also, have only opened them when I can receive 3 additional scrolls on the quest tabs for the month quests. I dont know if there is any kind of chance or way these work or its all mental chance in my head haha but sometimes its really worked for me in my favor.