BJ rolls with guys who are 200+ lbs and routinely submits them. A 155 lb Sherk won't be anything he can't handle. BJ also has a granite chin. A 155 lb BJ is too fast and slick for Sherk. BJ will reverse him and put him out with a RNC, a la Matt Hughes.
Team Penn
Sherk has explosiveness, speed, mental toughness over Penn, thats it. BJ has SICK wrestling, SICK BJJ, power in both hands, a granite chin. BJ was killing GSP prior to gassing (GSP TKOed Sherk), RNCed Hughes once, and was killing him prior to the rib "injury." Hughes won a lopsided UD against Sherk. BJ on paper should beat Sherk, whether he shows up in the shape necessary to do so is another story. I am hoping he does.