Evelynn is unplayable?
And I get all that. You can easily name one bullshit attribute on each champion. Like Vayne has true damage on her basic attacks, Shaco has a blinkinvisibility, Karthus has an ult that can hit everyone on the map for pretty high damage.
But then there's champions that have more than one of said bullshit attributes, that's when it becomes a problem for the champs with just one to compete with them.
Kassadin has a very low CD blink that deals AOE damage AND really good mana sustain
Lee Sin effectively has 7 abilities, is manaless, has literally everything; 2 gap closers, an execute, a slow, reveals, attack speed debuff, displacement, shield, tons of lifesteal in his kit
Yasuo has 2 passives for christ's sake
A good example of how a champ got balanced properly is LeBlanc. The fact she effectively had 4 gap closers AND a silence made her one of those champs. When they removed her silence she turned into a champion that wasn't overloaded with gimmicks.
That's how you balance champs. You don't adjust their numbers, you adjust their kits.
Have you seen Kayle be any less of a monster since her latest nerf? She's still pick or ban status. Same with Skarner. The nerf he got after his minirework hasn't made him any less viable.