Yeah Jacare is great and so is Marcelo.. Well both are amazing not just great. But Shields is more around Jacares size, and in an MMA match I think Shields give Jacare a little trouble on the ground, just purely grappling Jacare would beat Shields. I'm not claiming that Shields has better BJJ than Jacare, but I believe that Shields could still win the fight, and could catch Jacare.
I wish we could see Jacare and Palhares
Sig Credit - El Bresko