Tapping a black belt is one of the toughest things to do in MMA. Off the top of my head, I can only think of BJ Penn (KenFlo, Stevenson (might have been a brown belt at the time), and Hughes, who I'll talk about in a bit), Jones (Machida and Vitor), and Hughes (only BB he "technically" submitted was Almeida, but he TKOed BJ from a mounted crucifix and could have broken Royce's arm, but decided to pound him out instead out of respect). Hughes is also the only guy to have tapped GSP, although GSP didn't have his BB when that happened. I'm sure I'm missing a few...who are they? And who should get credit as submission artists for beating guys with great grappling who might not have been formally awarded a black belt?