Any context on the (rather heavy) nerfs to Skarner and Hecarim?

So looking on PBE it appears that you guys intend to nerf both Skarner and Hecarim in the upcoming patch. I'm surprised by this primarily due to the fact that they don't really stand out all that much at the moment. While I am sure you guys have some inside statistics that we don't, it would at least be nice to know what exactly stands out among the two. It would be a shame for Skarner to return to his pre-rework state (low damage, kited easily, basically a CC bot).

As for Hecarim, I have little experience on him so I'm not sure how to judge this. Those nerfs seem rather harsh though (mostly to his base HP). I hope that these changes (to be both champions) don't seem as impactful as they do on paper. I'd very much like to still be able to enjoy Skarner occasionally after 5.24.