Can we please have some context for the skarner changes?

I don't want this to come across as a "MY CHAMP IS DEAD RIP GG" thread, but I and some other people are a little puzzled by the changes to skarner--is there any chance we could get some context on the nerfs/changes? I recall that, originally, skarner was said to be a juggernaut/tank hybrid, and that although he had CC, he was still considered to be a juggernaut--generally meaning that he is supposed to be a substantial damage threat in close quarters, and less so from a distance.

From looking at these changes, it seems as though his juggernaut identity is being pulled back in favor of embracing more of the tank side--reducing the ad ratio on his ult by .6 means that he is ultimately rewarded with less damage for snagging a target, and the nerf to his spires means that he will be able to attack less frequently in his zones of power, further lowering his DPS at higher levels.

With the changes to the warrior jungle enchant and the buff to black cleaver's AD, it is understandable that skarner's damage might be a little TOO high, given the recent sizable AD increases to these items. But with the changes to mercurial scimitar (so there is no longer a tradeoff in sustain for buying it, meaning it can easily serve as a much more reactionary purchase to skarner's presence than it was before--at least, presumably) in addition to the general influx of ranged AD champions, I do feel as though Skarner really does have to WORK for his ults (usually expending a flash--although the addition of masteries that reduce the flash cooldown, along with easier access to distortion likely means that skarner can ult more often).

However, this is all speculation, and why any context that could be offered would be greatly appreciated. I'm just trying to understand the direction skarner is going in with these changes, and what they are a reaction to.