One of the major themes in this expansion was expressed by Sylvanas in the opening words of the Battle for Azeroth trailer: "Ours is a cycle of hatred." To demonstrate that there is a cycle, we created a story structure for Sylvanas that, on the surface, echoed many broad strokes of the road Garrosh took. A warchief promoted under questionable circumstances. A brutal act of aggression that instigated conflict. Distrust among the inner circle that led to an uprising. These parallels were intentional. But it's within the nuance that we sought to show the story grow and change.
The Horde believed that, by putting the wise Vol'jin in place as warchief, their future was secure. But they hadn't changed the underlying structures or practices that enabled Garrosh's tyranny in the first place. The untimely passing of Vol'jin and a bit of manipulation in the aftermath of his death were all it took for the pattern to begin repeating.