James Thompson is a "real MMA" fighter. James fought Fedor's brother and was in Pride several times. Same thing with Tank. He is a "real MMA" fighter.
I have followed Kimbo since his first fight on Youtube vs that guy named "Bird". Its the fight where Bird's eye almost falls off. Kimbo then had several backyard fights after that and then encountered Sean Gannon. Sean beat him b/c Sean was an amateur MMA fighter. I think Kimbo realized that he had to improve his overall fighting (not just boxing it out with guys), thus he got with Bas.
I'm not saying Kimbo is ready for Fedor, Cro Crop, AA, Randy, etc. He's just a beginner in MMA, he even stated it himself. He's got a lot to learn (ju-jitsu, kick boxing, etc), but he sure is entertaining to watch....