Riot, what's your take on these high winrate champions?

Was just looking at some third party website's winrate data: http://champion.gg/statistics/#?sortBy=general.winPercent&order=descend and noticed a couple high winrate champions that weren't getting addressed in the upcoming patch.

I know that these winrates can be off, especially when looking at things like soloQ vs ranked teams, and also with rank itself, so what is your opinion on: Zilean, Warwick, Heimerdinger, Kog'maw, Nasus, Brand, Shyvanna, Xin Zhao, Veigar, and Skarner?

Personal belief is that Zilean, Heimer, Kog'maw, Nasus, and Skarner are a bit too strong.

Zilean's problem seems to stem from the bonus AP he got from runes and maybe ultimate hat abuse as well. Heimer seems to just do a bit too much damage, not too terribly off though. Kog'maw feels like he has too much burst if he lands Q and procs Press the Attack. Nasus feels like he is hitting his power spike too early for the late game stacking fantasy to be fair. Skarner's CC from the changes he got look scary on paper.

Can't tell on Warwick as I have a huge bias on him, and I haven't had a lot of good games lately personally with him.

Anyways just had a few slight concerns and observations about these champions possibly being to powerful. Would someone at Riot be able to tell me if this seems true off of your data, and if any of these champions have nerfs planned for 8.3?