But AA doesnt fly JFK-PRG,BUD or VCE nor do I recall them ever doing so. So its when starting up new service they are doing so from its hubs other then JFK. DL flys to PRG and VCE from JFK.

AFAIK only BA,LH and QR have flights into PHL and 1 a piece. So although JFK may have the #s , PHL probably will allow much higher yields as there isnt any competition or LCCs to drive the fares down, and the flights will be seasonal