Ahri is just too dominant now
Ahri is simply too safe in lane.
No champion should have such an easy and carefree time in lane pre 6. Too many junglers have had their early game nerfed, and she was already hard to gank before then. The few mids that countered her pre 6 have all had their early games nerfed. Kat, Talon, and LeBlanc to name a few.
Ahri makes up for her mediocre early game, by being completely safe in lane until she gets her mid game power spike. Now that her usual early game counters have been nerfed she is safer then ever.