Why does mma fighter not do well in the wwe or tna?

there has been a big list of really good mma fighters that have tried to make the transition to pro wrestling but have failed.from the names like shamrock,dan severn,tank abott,and now most recently turki.he according to the wwe went like a 100-1 in his mma fighting over in pride or whatever but he didnt even get one big matvh in the wwe.i think that was due to the leaving of angle in the wwe which was who he was scheduled to fight.i know his mic skills wasn't very good thats why burke talked for him but mic skills are a learned thing really.