I would have thought with previous ORD-DUS they would have initiated PHL-DUS before PHL-TXL. Of course it would have been ideal when Air Berlin was still around but AA now seems to be doing point to point in Europe instead of funneling everything through LHR and MAD. They used to have a weak network to Europe but with US and PHL hub they now have a much better network to Europe - and DFW seems to be getting new routes as well.