Well...I don´t disagree with that actually..... Just said that in terms of grappling skills they´re the best...in a overall comparison between them and the others only in grappling atributes, they´re the best....
Jacare would outgrapple Maia at 185, in MMA imo. I think he is the best grappler. But in terms of who is on the list solid.
The list in the op looks like a current list. My all time list would probably be made up of the following, and not necessarily in order: Penn- Mundial winner, and one of the best fighters the sport ever produced. Nogueira- Would have been the best heavyweight ever if not for Fedor. Matt Hughes- High level wrestler with good submissions who dominated his division in spite of what was once atrocious striking. Randy Couture- Elite level wrestler that went on to win titles at light heavyweight and heavyweight. Couture eventually became a bjj black belt, albeit late in his career. Whether it was holding a fighter against the cage, dishing out some ground and pound, or winning by the occasional submission; Couture was successful doe to superior positioning. Couture's grappling allowed him to often dictate where the fight took place. Arona was all bjj and low kicks. Fedor was the best to ever participate in mma, and you can't be that great without a big time grappling game. Sakuraba has 16 subs in 26 victories, often against larger fighters. Jake Shields controlled Dan Henderson like no one I have ever seen, and probably has worse striking than Matt Hughes had 6 years ago. Demian Maia Miguel Torres
An all time list is difficult. I tried to take into account mma accomplishments as well as grappling ability. I didn't even consider fighters like Royce and Rickson, because of how much the game has changed since they were at there most successful.
I don´t know **** about grappling but Shields, really? He is one of the most one dimensional fighters since James Toney in the UFC and Mayhem almost submitted him. What about Barnett he is one of the best at putting wrestling and submissions together, he is without a doubt one of the most effective grapplers at HW
I don't know that you are questioning my list, but I assume that you are. That's fine, that list needs criticism before I can accept it. I have a lot of respect for Babalu, but I don't think he has strong enough wins for him to go in my top 10. On pure grappling alone, Babalu would at minimum hold his own with those guys. I did not compile my list in search of the best pure grappler. I was looking for the best grappler with the most mma accomplishments.