Rener Gracie, member of the legendary Gracie family that established the sport of MMA back at the very first UFC, and who popularized Jiu-jitsu, happens to be Punk's BJJ trainer. While Punk wasn't a full time student during his wrestling days, Gracie noted that his ability to retain knowledge was one of the best he had ever seen. That's high praise coming from someone with a storied background as a coach. Rener is the grandson of Helio Gracie, the creator of Gracie Jiu-jitsu. While the family hasn't experienced the same level of success in recent years as it did in its hey-day, Rener is a guy who knows what he's talking about. Punk appeared in one of Gracie's breakdown videos recently and looked very astute on the ground.