#3 Rowan doesn't have the necessary charisma to carry a program alone
I don't mean to sound disrespectful to Erick Rowan and dilute what he can do, but somehow he lacks the presence that a top heel should have. Maybe it's because he's been in factions for far too long, but he just doesn't seem like a main event player to me, right now.
There are rumors aplenty that he is getting the same push that Lars Sullivan was supposed to get before an injury put him back on the shelf again. Somehow Sullivan for all of his inexperience still seems like a bigger main event star to me, at this time.
But when you pair Rowan with Luke Harper, the equation changes significantly. Maybe it gets revealed in due course of time, that it was Harper who was the mastermind behind the attacks on Roman Reigns.
Maybe they both reunite with Bray Wyatt.