The UFC champion Luke Rockhold spent a few days in 2013 working on his Jiu-Jitsu with brothers Rafael and Guilherme Mendes at the Art of Jiu-Jitsu Academy in California.
Gui Mendes, who appears in this video (below) rolling with UFC fighter , assessed the ground level of the then Jiu-Jitsubrown belt in a interview with Tatame (in Portuguese)
“He is a brown belt and is very tough, even for someone who has a focus on MMA. He fights well in all positions and is strong. We do not think that he has that game on the ground that only uses MMA position. He has trained in kimono and has very good moves. “said Gui
Rockhold was a No Gi world champion at purple belt and is now a black belt.