#7 Matt Sydal
When Matt Sydal performed in WWE as Evan Bourne between 2007 and 2014, he appeared to have all the tools to succeed. He clearly had the in-ring ability and the look, but Sydal's size always appeared to work against him, before two suspensions for violating the company's wellness policy totally killed his momentum.
He was released in June 2014 after spending an entire year inactive, following his return from a serious foot injury.
Despite how badly his last WWE run went, Sydal remains an unbelievable talent. His time on the independent scene and in NJPW has allowed him to evolve his act, to move away from the reputation he had as a pure high-flier.
He's been involved in a 5-star rated match - a 6-man tag featuring himself, Ricochet and Will Ospreay taking on The Young Bucks and Adam Cole at 2016's PWG BOLA - and has solidified himself as one of the premier all-round talents outside of WWE.
The chances of it happening are slim, but Sydal seems like the perfect man to fill a gap in the mid-card of Smackdown Live. Matches and feuds with Sami Zayn, Dolph Ziggler and Mike Kanellis would surely provide high-quality television.