i have made a few post on how with maokai's reworked KIT can be effective and work if they tweak a few things
1st off his ult moves to slow, it needs to have faster movement speed when casted
2nd the cd of his ult is too long needs to be lowered by 15seconds at each rank
3rd the stun duration on his W is shit... and even when maxed it only goes from 1sec to 1.4 seconds
and 4th give him a slight boost in base ad and base attack speed early levels 1-3 even if you take away from later scaling
if this was done i think with out changing his damage ratio's or buffing any tank stats would make him more viable
and he can be fine if they do what i state with his ult and give him slightly early game buffs on his auto attacks and attack speed and give his W more duration on root.
what makes him bad is his stupid bad early game , in the past when his E had damage on impact even in bad lanes he could at least cs some now he cant even do that...
so to make up for it buff his early ad lvls 1-3 and attack speed , make his W worth putting more then 1 point into