Beating a 155er with no muscle mass when you are a very big 170 is nothing to brag over either. Especially when said 155er has little to no wrestling even in the 155 division.
BJ has some of the best. people say Frank Shamrock is the first true Mixed Martial Artist. but BJ is the first true elite Mixed Martial Artist. obviously he has some mental problems but there is no denying his all around skill set is phenomenal.
He will have no trouble handling Rory in the striking and grappling aspect of the fight unless(until?) he gases.