Thrall is badass. As it stands he's the most powerful Shaman in WoW history, even moreso than Ner'zhul before he went Warlock and became the Lich King. Part of WoW in the Caverns of time is stopping the Infinite Dragonflight from screwing up various points of the timeline, one point being Thrall's escape from Durnholde. As explained by the Bronze Dragons who guard and correct instances in time, should any of those events be changed, the universe would end. All of which are plots by the Old Gods who're using Deathwing as a pawn and have been for thousands of years. It took a race of Cosmic beings to lock away the Old Gods. FF is kinda lacking in that department.