I don't understand this:

JFK-BCN, direct, on AA in November, roundtrip:



Where did the 42,000 roundtrip figure come from? JFK-BCN falls squarely in the 20,000 Avios category and should be 40,000 roundtrip. It's still a good deal, though, with only $99.23 in fees/taxes, because when trying to book one-way on British Airways, you get hit with huge fees:



Does anyone know:

1) Why aren't one-way AA (or other Oneworld partners) showing up? They only show up round-trip.
2) How is it calculating 42,000 Avios?