For the BCA and later WPA pocket specs, its my opinion that they didn't actually "set" the specs. What they did is measure the most popular professional tables at the time, and made the "specs" to that. The old BCA specs were in the 5" range, which is a standard GC pocket. The more modern WPA specs are in the 4.5" range, which is the standard Diamond Procut pocket. Lets face it, Brunswick drove pool for the past 100 years, and Diamond drove pool for the past 20 years. The BCA and WPA did NOT.
Hanging our hats on anything they publish as "gospel" is BS IMO. For years, even the specs had huge typos on them, and no one even cared from their specs department. The typo had to do with the tolerance. It was something like 5" +/- 1/8", and got retyped years later as 5" +1/8". That typo was in all the dimensions that had tolerances, and was around for a good 20 years, probably longer.
We, as players, are more in tune with what's a factory pocket and what's a modified pocket, what's a hard pocket, and what's an easy pocket, than the BCA or WPA is, IMO.