Comparing JFK and BOS, the cheapest business class fares are both fare basis IEE14US1 , but from BOS it has a base of $8570 vs $12266 from JFK. Wouldn't a promotional offering likely be a fare base of its own?

Also, the BOS fares in economy class are more expensive than those from JFK which wouldn't be much of a promotion ( lowest base from JFK to SYD being LLW4PUS1 at $934 followed by LLWIPUS1 at $974 vs LLWIPUS1 being lowest from BOS at $1064 )