That repricing of one but not the other is a possibility. That is weird because those two sets are extremely similar and you'd assume if one set's prices were readjusted so would the other. I never asked for a price check on the 72-73s I am trading because there is nothing spectacular in the lot. Rotorob even mentioned the 71-72 Nate Archibald RC was $100 which matches exactly with my paper guide.
Curious as to what your OPG says the 72-73 Dr. J RC books for. Anxious to see if that changed from my 4 year old guide.
Beckett's has become exceedingly reckless and lazy in their pricing in recent years. When Kobe Bryant died his Topps RC went from $15 to $60 to a whopping $600 in a 2-3 month time period. Yet for years their paper guide listed a complete set of 96-97 Topps at $40 despite having a $600 card in it.