Agree with fatprop's recent post and that of earlier posts along the same lines.
I wrote in my match report that it was yet another occasion when the Wallabies faded in the 2nd half. I was happy with the first half forward effort though the Boks had a heap of possession. Fortunately they never looked like scoring a try with it.
Last year the Wallabies got a lot of early leads eg. Pretoria, Bloem and Sydney (3N) but the opposition finished more strongly than we did. At Twickenham we couldn't even get the early lead to fade away from.
There's a lot of reasons why teams don't perform well in the physical contests. Some of them are indeed physical and include a lack of fitness, including match fitness of players returning from injury. And there is also a lack of strength, as Bruce keeps advising us, after contact has been made. This matter is not well appreciated, as Bruce keeps saying.
But sometimes fellows are just rugby dumb and hang around too long deciding when and where to make an effort. They appear to be bludgers but they are not.
Good forwards are just like good backs: they have to make the right decisions and act on them instinctively. They know where to make an effort, usually at opponents near the location of the ball, and they have a better idea of when also. When counter-rucking this is usually early, to take advantage of the implacable laws of physics, but sometimes in a fetching situation it can be too early, especially for the 2nd man in (or "tackle assist").
Hopefully selectors take these things into consideration, together with set piece ability and the other stuff, when they pick their forwards. If the bench players don't perform as well as the guys they are replacing, though fresher, it could be a function of correct selection.
Sometimes our zip-zip backs are part of the breakdown problem. When I was a lad, back in the olden times, backs were instructed to make sure that they ran in front of their forwards unless a clear break was on. If isolated in front of defenders, they were told to run sideways to get in front of their pigs before they were tackled.
Our brilliant backs play too much low percentage stuff too often. As I indicated in my match post: sometimes it is better just to go to ground with the pill and in that context, their arriving backline mates should do a lot better than they do at the breakdown.
Accordingly, they should spend some of the next two weeks doing a bit of breakdown work.
But I digress - there is more to a lack of physicality than just at the breakdowns.