Shaco nerfs

What is the purpose of the AP shaco nerfs? I could agree that his ~53% (champion.gg) winrate is a little high and some tweaking could be done. However, if the current nerfs take it way to far. Just look at Ivern! He has a 55% winrate and there only going to remove 60 base health from his shield at max rank and nerf the slow by 1 second. http://www.surrenderat20.net/2016/12/129-pbe-update.html?m=1#more while there removing 200 base damage from the ult AND nerfing ap ratios of Q and E.

If these changes hit live servers it will make shaco a joke. The only viable build that remains would be some sort of bruiser/tank like Shaclone's build.

But as a Shaco main i know im biased. So could someone (preferably a rioter) explain objectively why these nerfs are deserved.