The only reason they made Mordekaiser into a bot laner is because they wanted to rush his rework
In order to make him a healthy Top laner they would have to rework his E and his R to be more than just fire and forget, but instead of doing that they just tacked on a 3 hit mechanic, made his W an actual spell, and added a Dragon. Now they nerfed him into the ground.
Give him a new E. Give him a new R. (Obviously he should keep the Ghost mechanic in some way)