That and the fact it was completely seasonal and had no feed. The only other long haul AA had at BOS was Paris and London. I don't think that since Boston wasn't succesful in recent ( boom times ) it will be more succesful due to an internal accounting whizz when it is very difficult in some firms to be approved allowed to fly on business.
I doubt seasonal VFR to the North West is at the top of the boardroom plans at DFW somehow. Could be wrong though. More competition IS good for fares but the flip side is that no one makes any money as yields dive. Hence you could have 2 Continentals, 1 Delta and 1 AA one summer and half that the next. as fleets go where the yield is. Be careful what you wish for chaps.
( happened at Glasgow )
It was partly the reason that BA left was that yields were falling. I know there were other reasons but the arrival of Delta added a lot of capacity.