Let's look at Nidalee's Nerfs in S6
6.6 - Passive no longer roots monsters 6.6 - Less Scaling on W (Human Form) 6.11 - Passive movement speed range from 5500 to 1400 6.11 - Nerf to W (Human form) Cooldown reduction 6.15 - R no longer resets nidalee's basic attack (Harder clears) 6.21 - Q, W, E (Cougar Form) All Abilities from 5 Seconds to 6 Seconds Cooldown
Nidalee's Winrate dropped from 51 to 46 during 6.21. Her winrate then dropped another 4%. Her current Winrate is 42%.