But Wrath stacks most certainly are a resource that will require management when playing WAR at "peak" level in progression. Even if every ability costs 5 stacks, the management is in the decision making.
You don't sit on stacks too long because it will lower your damage, but you don't use Fel Cleave whenever you get 5 stacks either, because you might not have enough for Inner Beast when the next tankbuster hits.
And there is also the timing of defensive abilities to take into considerations that will grants you additional stacks that you don't want to go to waste.