I think the only two comments I have about this above thread is that if you are stranded overnight off a BA flight, don't try too hard to find someone from BA, just book a hotel, doing your best to avoid extortionate rates, and send the bill in. We see almost no reports of that being denied, and none at all in the circumstances as reported above. So that's a level of comfort and consumer protection that travellers have on BA and other European airlines. Secondly if you are travelling BA, even on an AA ticket, there is some benefit in having the BA app, as a guest user. Almost certainly the Delta rebook would have been made mid flight and would have been visible on landing at PHL. Minimum Connection Time at PHL international to domestic is 90 minutes, so as soon as the robots knew you were well below that then they would have been searching out options. I make the actual landing time 17:20 versus a schedule arrival of 16:35. I would have hoped that was still a viable connection, but probably only to those on Global Entry.