To be honest, and this is coming from a lifelong Kevin Randleman fan, Kevin's raw athleticism was phenomenal, but he did not have the fine co-ordination and motor skills to really develop his striking to a level that would allow him to hang with guys like Chuck and Rampage consistently, let alone guys like Jones, Rumble and Gus and his chin was always a liability. He had no submission game whatsoever, either. Like, none. His attempt at RNC-ing Waterman (at least that's what I THINK he was trying) is one of the funniest moments MMA has ever provided me with.
Randleman was a phenomenal wrestler with good power and flashes of brilliance, but his mental game was always a limiting factor for him, as was his refusal to train at a proper MMA gym and develop all the skills you need to be a champion at the highest level. In terms of his career, there are a lot of parallels between him and Melvin Guillard in that they were both tremendous raw athletes that could never turn the corner into elite MMA athletes. Also, explosiveness and peroxide.