#5 Stacey Ervin Jr
Stacey Ervin Jr was one of NXT's more promising talents, a 25-year-old veteran gymnast who was receiving rave reviews from NXT professionals, performance centre personnel and just about everyone in WWE.
Despite having no wrestling experience it didn't take long for Ervin Jr to make his NXT television debut, however, his career would be cut short as he would pick up concussion problems that would force him to quit WWE and retire from professional wrestling altogether.
Although he never really got the chance to show what he could do, it's clear this was a big loss for WWE as a whole, and particularly it's developmental side who would've had him to point at as someone they've trained to be a wrestler.
Stacey Ervin Jr now works to help promote good physical and mental wellness and has released his own home-fit workout guide. Although I doubt you'll be hitting Moonsaults like he did.