4. Kelvin Gastelum
The youngest TUF winner in history and arguably the biggest dark horse also, Gastelum was hugely impressive in the latest Ultimate Fighter series. He was an underdog in both his semi-final fight with Josh Samman and in the finale against Uriah Hall, with the latter being particularly favoured. However, Gastelum somehow got past both guys and showed that he has great potential at just 21 years of age. His finale win surprised many as his opponent Hall was famous for knocking out fighters in spectacular fashion (see the Adam Cella knockout if you're unfamiliar). Gastelum stifled many of Hall's offences en route to a decision victory, winning the TUF crown and the 6 figure contract as a result. Since winning the TUF series, Kelvin has stated that he is going to drop in weight class down to Welterweight - which is unsurprising considering the softness of his physique. Gastelum should be even stronger and tougher by going down in weight as many in the Middleweight division would hold a sizeable advantage over him if he opted to stay at 185. As KG is just 21, he has many years to improve and this makes him a massive prospect. Many UFC caliber fighters hit their peak in their early/mid-thirties, so it may take over 10 years to see the best from Kelvin Gastelum - a scary thought considering how impressive he already is. At Welterweight, I'd like to see the TUF winner fight a proven fighter who is far from a contender in order to build a solid foundation to grow upon. Although a fight against the likes of Rick Story or Mike Swick could be possible, one name came to mind when I thought about KG's future opponents. Preferred next fight: Paulo Thiago