most guys in MMA arent BJJ masters.
they have solid ground games, but most arent as flexible or fluid on the ground as most of the guys that use rubber guard as a normal part of their game. its a hard move to pull, and its even harder to get a sub from it.
plus, its hard to pull rubber guard when the other guy is trying to punch you in the face.
only person i've seen use it is BJ Penn, but even he never pulled anything with it
HW: Cro Cop | Barnett | Gonzaga
LHW: Rampage| Shogun
MW: KANG | Sakuraba | Spider Silva | Baroni | Akiyama
WW: Thiago Alves | GSP | Mach
LW: Gomi | BJ Penn | Aoki | Jamie Varner reppin' AZCS | DIDA
9-7 in sig/av bets