Hextech Crafting and Mastery Ranking

I've played 8 games the last 3 days, maybe even more, and I havent gotten one. Single. Key fragment. I also have a lvl 6 yasuo, and went 9/0/7 a game, which lasted 20 minutes, And i got an A... other games, I've gone 31/8/something and gotten S- or A+... This gets many people tilted, and its so annoying... I understand, hextech crafting is a privelege, but priveleges are things that are available to us. This feels like I have to pay, to actually get the keys. I have friends who have the same problem, but with chests... Most games I play, and i do well, and i dont get a fragment or an S rank, and my feeding friends get key fragments EACH WIN. This is disappointing. Is 3 days of playing league and getting yelled at not enough for a SINGLE KEY FRAGMENT even? Or even a good score, not enough for an S? I would like this problem solved soon, or I'm going to get tilted more than ever...