Ken Shamrock, Barnett, and Sakuraba were representatives of Catch Wrestling, and they did alright and held their own for a while, but Catch has never proven to be the top of the echelon of ground fighting. Sakuraba had success against the Gracie's, but this isn't proof that Catch is better than BJJ. Similarly, Machida's success against Rashad Evans and Thiago Silva isn't proof that Karate is a better striking martial art than Muay Thai and boxing, because the success was limited to a short period of time and limited to just Machida and a few fighters.
The story of Karl Gotch easily broke BJJ guys' legs is the typical fairy tale bullshit that plagued the early days of traditional martial arts when there were no MMA to expose bullshit claims such as "touch of death," "secret martial art that is only known to a few monks that live in some remote mountains," "insert some martial art fantasy here."