intuition

I did a few dummy bookings and it seems

a) econ flex in the Japan joint business books into Y,B,H on AY, ie earns 150%. So they are not just normal econ tickets like I thought, and thus earns better. But you are left with only 2 AY options - cheapest flight with no flexibility and very low earnings or very very expensive full flexible ticket.

b) If you book from AY web site and choose to fly JL or BA, many times even the cheapest fares earns 100% or at least 50% to AY+. If you chose the AY option from the same search, it is always more expensive and never above 50% earning.