Why is Skarner being nerfed?

Seriously, they just reverted the nerf to his Q but now his spires - the thing he's supposed to play around - were massively nerfed and so was his ult's damage.

I thought Riot didn't want to nerf champion's strengths, especially those with clear counterplay such as Skarner's mechanics of crystal spires. I have no idea why he is being nerfed. He disappeared after the multiple nerfs he got when he came out and ruined the game, and I really don't think he's gotten any stronger on pre-season.