The whole mana cost of everything maybe an issue with druids, with the nerf to lifebloom and Tree form no longer reducing mana cost, I actually had to use an inntervate in 5 man, which never happened pre 3.02. But I hardly ever went oom before, now there is a chance.

From a gameplay perspecitve if everyone is your party is taking so much damage you are going oom casting wild growth something else is probably going wrong.