Patch 10.13 is over and we have quite a bit of data to compare to the 10.12 patch.
Vi, Lucian and Nocturne saw the biggest increases in win rate. Others stayed within margin of error. But Kog’Maw win rate tanked hard. Even after a buff to his AP kit. My guess is that people played him MID a lot more and struggled to make him work as AP champ in an uncoordinated environment.

Patch 10.13 performance

All Nerfed champions had their win rate drop. Most notably - Yuumi. Even her ban rate dropped by 17.5% Cassiopeia is quite an anomaly, she is being nerfed a few patches in a row now, but her win rate seems to drop, but really slowly.