these are the mythic rates as usuall, probably you will see such kind of post soon with the next mythic 
so…
5x 50gem chests =2250gems >> 250 x10 chance points = 2500
1x 50 vip chests =2250gems >> 50 x100 chance points = 5000
supposedly twice as much chance but you only get to draw 50 chests instead of 250… so rng can still do whatever it wants