Evelynn nerf feels warranted tbh, she can still oneshot once fed. Does her job as an assasain.
Obviously she is going to be bad in high elo, but its not like assasins are strong against cooridinated teams except for a few exceptions(zed but even he gets countered by stasis).
Not every champ champ can be viable at every level of play. And even if that was possible, it would be impossible to achieve over the span of even a year through buffs and nerfs