The difference is still there:
BA LAX-LHR, AS charges 70k miles plus $996, while AA charges 57.5 miles plus $732. Mileage difference is understood, but I'm surprised that BA's carrier imposed surcharges are over $250 more. True on all the BA non-stop award flights on 8/5 (just checked).
It doesn't have anything to do with POS or direction. Same POS, same direction.