It should never grant that much to begin with, Obsidian Mind barely gave you any super back in D1! Also ive recieved half my super back on multiple occasions when generating 7 orbs.
Um, as someone who mained Voidlock religiously in d1 - last season's Dire Skull worked about on par with D1 obsidian mind. Obsidian pretty much never left my head unless i was running sunsinger or playing pvp.
I used to farm the fallen on Venus by the Ember Caves almost daily - Nova Bombing the little group of around 7-8 adds (none yellow bar - just dregs, vandals and shanks) right before the stairs would net you your 90%-full super back every time...