The bolded part, that description exactly applies to their earlier match against Spain. Back then their defense was also very mediocre, did they play averagely and did they win on individual brilliance. The only difference is that Australia was simply playing better than Spain, which makes it that more obvious how bad Spain actually played.
I just realized that the Netherlands actually reminds me of Liverpool this season. They scored a hellish amount of goals, but Liverpool also had to take in a lot of goals, way too much for the #2 of the Premier League. The Netherlands is exactly the same. Van Persie and Robben are taking advantage of the mistakes of the opponents to their utmost efficiency. Fact is the weight of their team almost entirely falls on their attacking line. The moment something happens to that, they have a serious problem.
I do agree for most part; though they did play better against Spain. Especially the midfield 3 of De Jong-de Guzman-Sneijder were efficient against Spain. They were woeful here; though Australia played better even if Spain is reputed for its midfield prowess. De Jong was sloppy in passes in this match against Australia, though helped defensively. Sneijder was completely out of it - terrible in its passing and unable to inspire any creativity. Showing more and more than he cannot be a reliability like in 2010; though RVP/Robben seem to shine nonetheless. De Guzman had a good passing rate that was useless as if we look without the stat, most of his passes were backwards towards the back 3 or goalkeeper, and all 4 were pretty uncomfortable with their footwork and they considerably slowed any buildup in passing for Holland. Strootman is immensely missed in this squad.
There's lots of things that Holland failed to do in this match - it's not like they played the replica of their match against Spain but they found it harder because Australia played better. It's part of the story but not the whole.
As for Liverpool, the comparison holds true but apart the two goalscorers in Suarez/Sturridge, the young guns - Sterling, Coutinho, Henderson ect...scored a lot. The 2 world-class talents of RVP & Robben can provide the Suarez-Sturridge-like palette for the goals. But the youngsters should step up more in offense then, for Holland to flourish in that style more. All while, trying to play better in defense that is! Depay showed a start in that way, we can say. Perhaps him, Lens, Blind ect...can follow up more often when RVP/Robben are not on such a great day.