I think part of problem that Socceroos face with Asian qualifying is it's a huge confederation with some big distances to cover, and assembling a squad from all over the world. Basically same problem that AWs face, which would be even more highlighted if travelling all over Asia, rather than just the Islands which are a few hours flight from NZ.
A side like Saudi Arabia on other hand, is pretty much a team of domestic players from the Saudi league, or other nearby leagues in Middle East. So travel demands not as great, and get to spend longer together as a team.
In a one off game at full strength I'd pick the AWs verus Saudis to be very tight. But the AWs playing a long Asian qualifying series over 1-2 years may struggle with travel demands, and constant unavailability of senior players.
Anyway it's all a bit irrelevant as will never happen, especially with WC to be expanded to 48 teams, and we get our soft entry, with clayton's two games at the big dance.
Hopefully FIFA's proposed Nations League gets approved - so giving AWs some meaningful quality games both home & away.