The ELO mode is different, randomness is very limited.
That explains a lot about why I ain't been doing so well on ELO! Thats the first time I have heard that.
In ELO, randomness is reduced a lot and "impossibles outcomes" will not happen (like 1 atq vs 64 atq, 1 atq wins). There is still random (because we believe it's FUN!)
Knowing when to take a hit, and how to wait, is more important then luck.