DOesn't matter if Rickson was another level to Renzo on the mat, Saku would have denied him access there and hurt him standing/ By the time it hit the ground, Rickson would be too hurt to do much to him.
Look at it this was-rickson would no way in hell have been able to take down Saku, hold him down to control and submit him. In his prime, nobody was able to take down Sakuraba, hold him down, and control him. Bigger strong wrestlers were able to take him down but not control him nor had an easy time keeping him down. Rickson being a lighter and weaker wrestler compared to his other opponent s sure as hell wouldn't have been able to do it
During that time, beating Funaki in MMA meant nothing and beating Saku meant everything. RIckson never fought Saku but Wandy was the one to derail Sak
I would have loved to see Wand at that time fight Rickson