I can see how some of the ORD-LHR passengers would have switched to AA. I can't imagine ORD-MUC passengers switching to AA, but possibly to LH.

I had booked ORD-FRA in C that downgraded to old C at T-48 and asked to switched to the IAD-FRA flight for lie flats. Unfortunately the connecting flight to IAD went mechanical, so eventually had to go through EWR. Although LH doesn't have lie-flats on the business class, I don't think there is a reason to fly UA TATL as they can always downgrade to old business class seats. If you are buying economy and upgrading with SWUs, that's a different story.