Originally Posted by
percysmith
Interesting theory but doesn't match the facts - Y was booked out/(withdrawn from sale) first - as of 24 Apr I saw J2 Y0
Most of the time, when it gets close to the departure date, CX begins releasing J inventory to Y. Some Y passengers will get op-upped.
When they overbooked two more Y, they released the two J to Y inventory (J2Y0->J2Y2), which was immediately taken and J2 will become J0 (J2Y2->J0Y0). If it were J0Y2, then there would be no overbooking.