I feel that he's been gutted with nerfs and unnecessary adjustments. I remember last year when he first came out and everyone hated him, but I loved playing him you can be a bully, passive, or even carry support due to the damage he had. But, now he's pretty much just a meat shield and with this seasons never ending nerfs on movement speed he can't really have those heroic saves when a gank is coming in, since he no longer get's movement speed when devouring allies and running away, which is used way more than running towards enemies.
His style now is less reliant on Devour, since you need all of his stacks to get the most bang out of his attacks it's pretty much a long string of tongue lashes and basic attacks then maybe finish the enemy off with it. The shield nerf from a 6 second decay shield to a 3 second solid shield still saves, but was unnecessary.
Jungling with Tahm Kench now is impossible he can still 1v1 on top lane just as long as it's not a tank or anti-tank like Shen, Malphite, Rammus, or Trundle. Supporting with him has gotten harder, since he doesn't really have much of an escape for his adc, due to the Devour movement speed nerf. But, his harass is still good just need to be a bit more accurate, due to that tongue lash nerf from a while back but that's whatever. He no longer get's that lvl 6 power spike anymore, which I have no clue why they would move the ult passive to be apart of the stack passive. If you pay attention to his stats his early game is typically good he just falls off if they game goes on too long.
I understand riot tried to "Unbench the Kench" but all they did was put him even further on the bench it's almost like you wanted to make him how old Yorick was, Unplayed and Forgotten.
until they got nerfed 
