Key fragment gain even closely balanced ?

I have 22 chests, 2 key fragments and 0 keys...

As we know, the chest per champ resets every season (?) and I have played a lot this season, at least +7 games with every champ I have gained S (gained chest) which is roughly 35 champs * 7 = 245 games + random champ tests + playing more games with main champs... So how is +245 games not enough to get key fragments enough to unlock all the chests I have acquired? Or is RNG just not on my side?