the downgrade is due to demand so it seems that VA is suffering a bit.
Both QF and VA have suffered poor loads on their A332 services between BNE and PER. QF have scheduled 763s on this route a number of times and it looks like VA have also realised that the A332 is too much plane for the route. The 738 is a bit of a come-down from the A332 in J class but it isn't much different from the J class on QF's 763s or domestic A332s.
Hopefully this is a sign that there is a bit of common sense returning to both airlines after the stupid capacity wars of the past 18 months.