Vayne now has the #1 pick rate in the game
...and a 51% win rate. Yet still no word from Riot on nerfs. I'm sorry, but I have a problem with any hyper carry having a safe early game. Riot needs to nerf her early game or nerf her late game.
EDIT: Adding this in since I am getting this question a lot.
I agree 51% is about perfect for win rate, but there is a lot more to look at than just a champions win %. There are TONS of champions who were obviously OP and were nerfed even though their win percentage was below 50. When you have a champion being played the most it means a lot of non-mains are playing that champion and doing well with her. You also have to factor in that the main opponents she is going against are other ADCs that are very strong right now (i.e. Jinx and Tris).
She would have been fine, except for the fact that Riot nerfed her counters so hard. So now she is the one who is OP. It's just a weird cycle the game goes through whenever they change the meta.