Rengar is the lowest winrate jungler, what now?

I don't understand how balancing him can be so hard. The Q makes no sense as it just promotes him to build tankier because of AoE. Same goes for his ferocity system. His ult is now basically a zoning tool for pro play but that's pretty much it. Like, you remove him from preparing old Q before jumping, but instead give him free crit to compensate?? How does that make any sense?

On top of this Riot said that they wanted him to remain an assassin. Welp, there goes that.