4. Alex Shelley 
TNA has had a long string of undersized wrestlers playing the underdog champion role in recent years-- Chris Sabin, Austin Aries, Eric Young-- but, Alex Shelley should have been one of those names. The growth in which Alex Shelley showed between 2004 and 2010 was remarkable to watch. He went from basically a filler act into one of the more refined and well-rounded cruiserweights in the world in a short amount of time, even reaching #32 among PWI's top 500 wrestlers in 2009, and tag team of the year with Chris Sabin in 2010. Beyond his improvement in the ring, Shelley was a weekly highlight on TNA Impact for months alongside Kevin Nash, when the two participated in the hilarious "Paparazzi Productions" segments. In a company that has traditionally struggled as it pertains to backstage promos, these were some of the most entertaining of the era, let alone of each respective show. Despite his constant displays of ability, Shelley was never given an opportunity to grab the brass ring in TNA, even when his partner Sabin missed two years due to consecutive torn ACL's. In 2012, Shelley opted to not re-sign with the company, and his former partner would go on to capture the TNA title. At just 31 years old, Shelley has plenty of time to make his mark on the main event scene in professional wrestling, regardless of the promotion,