Azir's winrate dropped by a whopping 10% after his nerfs
Azir's winrate pre-nerf was nothing special, it was a mere 47-48%. After the nerf, it dropped to 38% (35% in diamond). This is even lower than Yasuo's lowest ever winrate after his gutting, and lower than release Azir win-rate.
The nerfs were absolutely too harsh, and I experienced them first-hand by trying him out. He just doesn't feel threatening at all, even when ahead, of course provided that he can get ahead.
I think Riot didn't test the impact of the changes properly, and now has to buff him back to viability. The range nerf hurt him the most. It was completely unnecessary, provided his Q damage, which is his main source of damage until he gets 2 or 3 full items, got gutted as well.