I'm of two minds about Skarner. He was my main in ranked since release and still stands as one of my favourite champs in the game. But the nerfs to his ult and the cooldown to W really hit him hard. They damn near castrated him with that change.
Its hard to place why it had such a huge impact, the s3 item changes weren't great for him but there were a few upsides (iceborn gauntlet, boots of swiftness and spirit of the elder golem were all nice changes). I think the bugfix on his ult just drastically reduced it's effectiveness against highly mobile champs. And now we're in the league of gap closers that effect is just compounded. He was never the best tank, or the best damage dealer. He was a scud missile, picking out a champion and sticking to them no matter where they run. Now they've taken away one of the most important aspects of that he just feels sub par.
Reverting the changes would fix the problem but im not so sure that is the way forward.