#4 Emma

Emma lays claim to the unfortunate honour of having seen her run on the main roster fluffed not once, not twice, but three times since initially making the jump from NXT.
Having spent time in both Florida Championship Wrestling and NXT, she was very much ready for the big time by the time she graduated in 2014. But after a year of uninspired back-and-forth booking, Emma found herself back in NXT in early 2015.
Female superstar says she inspired John Cena turning heel HERE
There, she once again proved herself—not least of all in her Takeover: London match with Asuka—before re-debuting on the main roster under her new heel guise. Except, the return came in rather muted fashion on an episode of Main Event, and by the time she went down with a back injury in May her momentum had already been lost anyway.
That layoff then gave way to the infamous Emmaline vignettes, which lasted a ridiculous 17 weeks before the idea was scrapped altogether and Emma eventually returned as her plain old self.
Then again, at least she still had an awesome entrance theme going for her, which is more than can be said right now.