Warwick may not be OP but he is a lot to deal with

He builds tanky AD items, yet is doing magic damage on hit and from abilities. He scales of AD and AP, AND does % of health..starting at 10 percent. not like, 6, 7 8 9 10..nope, immediate bonus damage of 10 percent of your max health.

He gets built in movement and attack speed from the same ability, passively deals magic damage and heals himself in an Aatrox style manner which is supposedly toxic, reduces tons of damage and then fears you.

This is another example of Riot reworking a champion and overloading their kits. His kit allows him to have a wide range of viable builds, and I think you are going to see his win rate rise and eventually get nerfed like Poppy.