If Kosak wasn’t involved in Cataclysm’s Lore Afrasiabi would have made Sylvanas into the Villain of MoP…
Afrasiabi was in charge of the Revamped Zone Quests while Kosak was in charge of the Expansion Quests(Vashj’ir, Hyjal, Deepholm, Uldum and Twilight Highlands). Afrasiabi is the one who made Garrosh be a good person in Stonetalon Mountains while Kosak had him recklessly attack the Alliance in Twilight Highlands!
Garrosh being handled poorly led to Sylvanas being handled even more poorly!