I've been training MMA athletes for about 10 years. I train a guy that's an UNBELIEVABLE in bjj. I find that muscles trained to be efficient in bjj is not the same as the muscles required for speed/power work. In stand up speed/power is critical. I combine plyometric (HITT) type training and weight lifting in the workout to condition both the quick twitch and slow twitch muscles. The the original question about BB good for MMA? My answer would be "it depends" on the training. Weight lifting is definitely good for MMA. The BB physique is not the ideal body in MMA.