THAT was your maokai nerf
If maokai is your baseline for what tanks are supposed to be... Why is every single freaking other tank(other than 5.5 sejuani and current nautilus) BELOW that baseline. Congrats you reduced his passive by 14-24 health per proc which amounts to like 1/4th of an auto attack! He will still be in every single professional game. Many matches seem to become maokai and whoever you can face off against maokai with (currently hecarim who received a significantly more meaningful nerf than maokai did).
Why not also knock 5 damage per level off of his arcane smash or sapling or something like that as well or reduce his passive to 6% across the board since that 1% is meaningful when maokai has 3-4,000 health(30-40 less health every passive proc late game would be a meaningful nerf).
Or if you want to leave the late game, hit maokai's base health regen on top of the passive nerf so that he can be pushed out of lane early on?