A very interesting post, and one that I have not seen before - due to the rarity of two people travelling on the exact same fare who are willing to share details.

Is there any other variable in there such as an ABN (business rewards), special meal, different state on the contact address, TA vs QF web booking, booking time.

The only other thing I can think of is what is often reported on BA, that the IT behind the op ups will often prioritise someone who (a) normally buys J but did not on this travel and/or (b) low status but with an accelerating flight pattern in the hope of regaining or buying some loyalty. i.e. the BA Golds/GGLs are often not the top of the upgrade list.

Could be that QF sees the Plat as sometimes buying J so why incentivise as you may be willing to play the roulette again if the price is low, vs a QF Gold who say has never flown in J they might want to make a smaller marginal cost to encourage them to buy J, to then create a pattern. Of course the big assumption is to have a top J product that gains ongoing loyalty...

While I am rarely positive towards QF, I do think that their yield management, customer encouragements and upgrade algorithms are first class, so I would not be dismissing this off hand. It will be well thought through.

KF