I don't have so much faith in Riot's character designs. There's already so many champs that it just paradoxically gets more and more boring with each champ update. Problem with Kayle is, you don't know how to treat her. Like melee or ranged? AD or AP? They don't seem to have an idea what to do with her, since pure hybrid is quite discouraged, she's not Jax.
And rawr, AP Yi isn't THAT bad, he can deal a lot of damage, especially when he gets Lich's. But other than that, MR. It's same for Wolfie, I saw an AP Wolfie that dominated a game, but yeah, no.