I'm very new to jiu jitsu, I've cross trained in a lot of different arts in the past, but never really dabbled in JJ.. my question is: how effective do you find your JJ is against a really strong, juiced up opponent. I've rolled a few times with a buddy from Brazil who trained with Wandi and a few other top guys and he had trouble submitting me a few times (though he submitted me plenty, lol) because of the sheer strength and size difference. He's about 5'7 170, I'm 6"1 245-255. I'm sure my knowledge of other arts helped me out some of the times as well but overall how do you guys find you match up against someone like that, who is a trained striker (MT, boxing, systema) by nature?
Also, do any of you guys ever worry about having a glass jaw, I've sparred with a few JJ guys before with gloves and shots to the face, a lot of these guys couldn't take shots/had glass jaws.