Australia's best young rugby players got a whoopin' this week from an awesome baby All Blacks side.

From an Australian perspective, the final of the Junior World Championship in Argentina was hard to watch at times, such was the dominance of the young New Zealanders.

But the big picture needs to be considered here. The Aussies played some wonderful football to make the final, beating South Africa and England along the way.

Being monstered 62-17 in the decider leaves a bad taste in the mouth, but for under-20s, maybe that's not such a bad thing. Australian rugby players are traditionally clever. They'll learn from this and set up a great rivalry between the next generation of trans-Tasman rivals.

However a harsh reality of that game and the performance of the Wallabies in the two Test series against England this month bring into sharp focus an Achilles heel of Australian rugby and it's not just the Wallaby scrum which was comprehensively outplayed in the last two senior matches.

It's as much about the other collision points in the game. The hot ‘n' cold Wallabies, especially without first choice players such as Wycliff Palu, Tatafu Polota-Nau, Digby Ioane and Benn Robinson are overmatched physically.

At the best of times, the dancing feet of the Aussie backs save the Wallaby bacon, but without at least a few impact players crashing over the gain line or muscling up to straighten the attack, the Wallabies' physical deficiencies are cruelly exposed.

In combination with a scrum that is tumbling backwards or at the least straining to win its own ball, the Australians spend a lot of time on the back foot or being forced to defend bravely, as they did in the first Test against England (not-so-much in the second which was a horror show).

It goes some of the way to explaining why the Wallabies can look wonderful one week and woeful the next. Scrum aside, they played like geniuses in Perth, but it's a rare team that can expect to play with that much attacking and defensive precision, game in and out, particularly when your set piece crumbles like a biscuit.

Ironically in the junior championship final, the Australian pack, which is in fact about 10 kilos heavier than the senior eight, faired fairly well in the set pieces, but across the park, in one on one tackles and especially at the breakdown the New Zealanders smashed them.

The strength of the baby Blacks and their ability to counter attack with directness and speed was breathtaking. They simply didn't let Australia play, knowing the junior Wallabies had great success earlier in the tournament holding their own in tight and playing an entertainingly expansive game.

That's the kind of rugby the senior side want to play too, but without their injured impact players they too will suffer against committed, physical opponents.

A Wallabies team with Nathan Sharpe and James Horwill winning lineout ball and tearing it up at lock; Palu hitting it up, Robinson, Polota-Nau and Ben Alexander hustling up front and game winners like Quade Cooper, Will Genia and Ioane taking the advantage of the go-forward is capable of anything.

But the return of some of the injured standouts is a way off. That means it's now or never for workhorses such as Richard Brown and Dean Mumm and backup players including Matt Hodgson and Mark Chisholm.

If the Irish add to Australia's woes in their one-off Test in Brisbane on Saturday - and they shouldn't, given they are missing at least a half a dozen of their best - perhaps it's time for a radical rethink, at least in the short term.

In the forwards, Queensland's Rob Simmons, the Waratahs' Kane Douglas, even a fit Leroy Houston might not be quite ready for the biggest stage, but could bring a different look. After all, others have had their opportunities and are yet to grab them. In the backs, Adam Ashley-Cooper, in Ioane's absence, must always be a first choice player and you'd think Peter Hynes' ability to do the unexpected occasionally would be a valuable asset.

It's not going to happen, as Robbie Deans completely overlooked Pat McCabe for his expanded squad, but it's not difficult to imagine a hard running, accomplished back three player like the Brumbies winger would inject some of the directness Ioane usually brings in attack.