Eve isn't useless in her current guise, just really needs to be partnered with a team that has stuns. You can still be very effective with her and win games, stealth is still incredibly powerful.
There's a lot to this game that people tend to gloss over. The champions, runes, masteries and summoner spells you pick need to match up well, they need to allow you to perform your given roles to the highest standard against the combination of champions, runes, masteries and summoner spells you face up against on the opposite team.
Level one fights (or not), lane management, lane harassment, jungle route/technique, gank timings, wards, how you spend your money, what items to buy first, how to counter opponents, is your team stronger early or late and how can you take advantage of that, dragon, red buff/blue buff (who gets them?), when to team fight, when to push towers, how to push towers, is your team more or less sustainable than theirs?, when to do baron and much more.
A lot of these things should be considered frequently, but most wont get a second thought in the majority of players' minds.
It's this level of complexity and variety that makes the game so enjoyable for me, although I do wish Riot would do a little less tinkering for the sake of it.