A big factor is also indisciplined bowling from SA at the start of 1st test and also now at the start of 2nd test. Lack of any warmup or domestic games for SA could be a reason. Also, one must remember that pitches is SA/Aue are identical. So, neither SA nor Aus needed to do too much adjusting to play in Aus/SA. And finally, for some reason, Smith just does not the same guy that we saw in Aus.
It is a misconception if people think Aus will go downwards the WI way. Their cricket system is good enough not to allow that. What the retirement of the PSYCHOS have done is brought them back to the pack wheren games between the top tier teams, which is right now Aus, Ind, SA will eb competive.
The 2 scoreline of the 2 series put together is 2-2 with 2 tests still to go.