6. Kevin Randleman
http://www.youtube.com/watch?v=A_XlUSmJBC8 Kevin Randleman's inclusion may be a surprise to the hardcore MMA fan as he did achieve a fair bit in his career, but for me he could have done much more. A former UFC heavyweight champion in the dark ages who notched up wins over impressive guys such as Ninja Rua, Mirko Cro Cop and Pedro Rizzo, Randleman is mostly known for his incredible athleticism and powerful physique. At one stage in his career, The Monster was 14-5 with a 3-0 Pride record and 4-3 in the UFC. Hardly anything to be ashamed of. That's when it all went downhill. Although Randleman went on to defeated the aforementioned Mirko Cro Cop in one of the single most shocking victories in MMA history, he then went on to post a 2-9 record including a loss to Cro Cop, who decisively avenged their earlier outing and proved that flukes do happen in the sport. Regarded, KR has lost to some of MMA's greatest - from Fedor Emelianenko to Shogun Rua - he is another case of a fighter that could have achieved great things and been noted down as one of the greatest, but was never able to. The main reason for this is his inconsistency; one fight Randleman can look incredible, strong, quick and then the next he can look sloppy and lose to a guy who he should easily defeat. Now 17-16 as a pro, Randleman has finally decided to call it a day and is unlikely to return to the sport as his last fight was two years ago. The Monster was at one point in time very promising, a former UFC champ and in Japanese promotion Pride FC demolishing guys, but his lack of consistency was the issue. However this slam against Fedor will be remembered forever as one of the most brutal moves in history:
http://www.youtube.com/watch?v=IDB8wk6P9g8