#4 Baron Corbin
Baron Corbin has had an entertaining run as RAW's Constable and Acting General Manager, but he's just one of those superstars who can't seem to get the big one.
Admittedly, WWE has pulled the rug from underneath him multiple times, particularly when he was Mr Money In The Bank. However, Corbin has yet to prove himself to be a WrestleMania main event-level star. He has a long way to go, but he just doesn't seem to have it in him.