#5 The door to the main event is open

The main thing which was disappointing about Dean Ambrose's heel turn was the fact that his career-defining feud with Seth Rollins was so lacklustre it was unbelievable.
As this is one of the few narratives in WWE that has substance to it, so by booking it in such a mediocre manner WWE sort of ruined its unique feel, as fans no longer care about the problems between these two former Shield brethren.
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And it seems as if Seth Rollins has moved on from his storyline with Ambrose, as he is now focused on a new path that leads him to Brock Lesnar at Wrestlemania, and this sums up the argument of why Ambrose should be added to the Universal Title match at the Royal Rumble.
As Ambrose getting back in the main event picture could set him and Rollins up for another war down the road, as many expect Rollins to win the Royal Rumble and become the Universal Champion. So Ambrose getting a taste of Wolrd Title glory while his biggest rival holds the title would be a great catalyst for another showdown between these two.
A top WWE star is missing in action