Jerome showed that he can compete in MMA. He didn't really looked like a total fish out of water. Current Mirko hasn't exactly been the most impressive fighter, so Jerome could very well beat him, given that Jerome has MMA experience, looked pretty solid in there and could just walk Mirko down, since Mirko has shown that he can't fight guys who bully him around.
This whole, "Jerome hasn't beaten anyone in MMA, while Mirko was PRIDE KINGZ LOLZZZ!!!" shit doesn't really work, since Mirko hasn't been the same since Gonzaga killed him.
In case u didnt see his fight against ambrizlebanner was losing that fight due to his wrestling or lack thereof and only won becauseamrbriz gassed and the ref stood themup.
The sappfight he got outwrestled which is almost funny.
Cro Cop doessome of his best work against the veryfighters that lebanner has had his problems in mma against put lebanner in against aleksander emelianenko and see what would happen.Or better yet see how long hed last against fedor.Cro Cop went to the D with fedor and won against his "little" brother.