Sometime during Pakistan's first full day in New Zealand, some of the players might have turned on the television to watch Australia's fourth innings in Perth. They will have seen Kagiso Rabada doing what he does. And beyond the admiration for his skills, there will have been envy - what Pakistan would give to have their own Rabada right now - followed by a sigh, because they would remember, more than most, that it wasn't long ago that Pakistan seemed to hold the trademark on young speed demons.

Last month Bangladesh's Mehedi Hasan became only the 13th player to take a Test five-for before his 19th birthday. Of the previous 12, six were Pakistanis, four of them fast bowlers. And that list doesn't even include the likes of Mohammad Sami, Mohammad Zahid and Shoaib Akhtar, all of whom managed the feat in their early 20s.

It is in this context that the supposed current travails of Pakistani fast bowling are measured. Of the five quick bowlers Pakistan have taken to New Zealand (Mohammad Amir, Imran Khan, Rahat Ali, Sohail Khan and Wahab Riaz), and will most likely retain for the Australia leg of the tour, only one is under the age of 28 - Amir, who has already lived a life far more eventful than most people his age have done.

The tours to New Zealand and Australia are significant - perhaps the biggest since, well, this summer's trip to England. And despite the players' protestations about how the Tests in New Zealand are likely to be more difficult than those across the Tasman Sea, it's obvious where their legacies will be defined.

Pakistan haven't lost a Test series to New Zealand in 30 years, while their two wins in Australia since 1980 came in dead rubbers after they lost the series. The tour to Australia is how ex-players define how hard Test cricket is. They tell stories, of big, hairy men, ready to kill them at a moment's notice.

Pakistan will go to Australia for the first time in 17 years with a realistic chance of returning victorious. But, perhaps for the first time in living memory, their worries are primarily over their fast bowling.

"During Wasim Akram and Waqar Younis' golden period - 1990 to 2003 - the other fast bowlers combined to average 34 with the ball. That's the same as what the current five fast bowlers achieve"

It's an odd feeling for a Pakistan fan. Decades of experience tell them that it will be up to the team's batsmen and spinners to ensure that the fast bowlers' efforts won't be in vain. And while over the last six years this team has busted one Pakistani myth after another, it would appear that their brand of spin-heavy control cricket might finally come undone down under.

Twenty months after Wahab became a household name, 11 months after Amir made his return to the national side, the concern for Pakistan fans, and their captain, remains with the fast-bowling unit. This isn't what the script promised.

There are a lot of reasons for why Pakistan find themselves in this situation. As always, the finger-pointing goes back to domestic cricket, where a combination of helpful pitches, substandard balls, and the fact that the cricket season is in the winter end up helping medium-pacers and discouraging old-school Pakistani fast bowling. The result is that in the current season of the Quaid-e-Azam Trophy, there are as many as ten medium-pacers who have taken over a dozen wickets at under 20.

Then you have to consider the nostalgia bias - far more prevalent than any recency bias - that affects the Pakistani cricket fraternity. If they are to be believed, there were a dozen or so fast bowlers in the '90s who would have all been world-class if given enough of a chance (usually stated as: "If Wasim and Waqar hadn't destroyed their careers"). Yet the numbers don't bear that out. During Wasim Akram and Waqar Younis' golden period - 1990 to 2003 - the other quick bowlers (those who took at least 20 wickets) combined to average 34 with the ball. That's what the current five fast bowlers achieve - mostly in less helpful conditions.

And that's the crux of the issue really. The myths that feed Pakistani exceptionalism might proclaim otherwise, but has there ever been that much depth? Right now Pakistan are operating with what should have been their second-string attack. Is this attack's performance any worse than those achieved by second-string attacks in the past? And are these bowlers as bad as is being suggested? Not really.

Amir still doesn't have a full season under his belt; Rahat performs a very specific role, which he has nearly always succeeded at; Imran and Sohail, in helpful conditions, have delivered repeatedly. And Wahab is far better than his critics suggest. For all his proclivity to being smashed around like a drum, only four bowlers who have taken over 30 wickets in Asia over the last decade have had a better average than him.

For all their limitations, the West Indies series, where they supposedly failed to turn up, was an exception rather than the rule for these bowlers. For six years they have operated mostly in unhelpful conditions and delivered more often than not.

But as always, the thoughts turn to the what-ifs and the potential. That's why the young speed demon will always be favoured, for his promise makes even his possible ineffectiveness worth it.

In that ideal world, Pakistan would have gone on this tour with an ageing Asif ready to say his goodbyes, having spent six years tutoring Amir and a Junaid Khan who wasn't made of papier-mâché. With Wahab ready to bowl on tracks that suit his style of bluster, Pakistan would have started the New Zealand series with fast bowling their strength rather than their supposed weakness.

In the real world, though, Pakistan have travelled to the southern hemisphere with five pacers, all with question marks over them, wanting to change history. They may be able to affect what will happen, but they'll never change what has already gone by. And that, it would seem, will never be good enough.