Fuck, now you've got me rewatching this fight. Sigh.
As Parillo pointed out in the article linked above, this shit never made any sense from the start. Edgar was either #2 or #3 in the world at 145 at the time and had two* previous wins over BJ. BJ was retired and returning to a new weight class, and instead of having him take on a couple of top 15-20 guys to see if he could compete/deal with the new weight, they throw him in there with Edgar. Fortunately in the present day they're giving him a guy who is a more realistic test for him in Dennis Siver.