#2 Dean Ambrose

The Lunatic Fringe was expected to team up with Rollins and win the RAW Tag Team Championship late last year.
Rollins, Ambrose and Roman Reigns reformed The Shield in the second half of 2017, and while it was one of the most highly anticipated reunions in recent memory, it didn't quite materialise as WWE would've hoped.
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Instead, Ambrose suffered a triceps injury, and was forced to visit the operating room, while Jordan stepped up and took his place. Jordan and Rollins won the RAW Tag Team Championship, before dropping the titles to The Bar.
It was also rumored that Ambrose would turn on Rollins and Reigns on the road to WrestleMania 34, thus setting up a showdown with Rollins had he not suffered the injury.
It was then announced that Ambrose would miss in-ring action for nine months, pushing his return date to August – around SummerSlam season.
WWE could always go back to their original plan, having Ambrose ambush Rollins, setting up a rivalry between the two going into Survivor Series.
Source: http://www.wwe.com/shows/raw/article/dean-ambrose-surgery-update-dec-2017