Kat's win rate has fallen 3% in ranked
From lolking, her ranked win rate which averaged around 55% (54.64% on the 24th) has fallen to 51.75%. Still a decent win rate all things considered but I think we can accept that the nerfs make a difference now. She doesn't just "get easy pentas gg" all the same. Also, interestingly, the decrease in her win rate seems more extreme in lower elos (Bronze) than higher ones (Diamond). So it looks like this also increases her skill cap.