When does a string of aberrations become a pattern? When does a blip become the norm and when does continuity of selection become rigidity of selection?
These are the questions England need to answer after a painfully weak display of batting left them requiring something approaching a miracle to avoid defeat in the first Test of the Ashes series.
On a pitch that remains sound and true, England collapsed from 82 for 2 to 91 for 8 in a session that brought back memories of the dark days of England cricket in the late 1980s and 1990s.
There are, as ever, some excuses. First and foremost, they came up against a fast and unpredictable left-arm bowler who rattled them in a hostile spell of sustained fast bowling. Mitchell Johnson deserves great credit for this.
England might also point out that rain has robbed them of time in the warm-up games and training sessions and that both Kevin Pietersen and Matt Prior's preparations were somewhat disrupted by injury. It is true, too, that this pitch was some way quicker than anything they experienced in the recent series in England.
But most of those excuses are pretty thin. It's not as if they could not have been predicted. It's not as if England have not faced Johnson before or as if they have no experience of these conditions. They knew what was coming and, by the evidence to date, had either not prepared adequately or failed to execute those plans.
Nor is it the first time they have started series with a poor batting display. They have failed to reach 400 in the first innings of their last nine Test series - a run that stretches back to the start of 2012 - and on five of those occasions have failed to reach even 200. If an event keeps occurring it cannot be described as a one-off. It has become a recurring failure and one that should be keeping Andy Flower and company awake at night. This has been, for several reasons, an accident waiting to happen.
On paper, this is England's strongest batting line-up for many years. Pietersen and Alastair Cook have scored more Test centuries than any men who have previously represented England and may both be remembered as greats of the game; Ian Bell and Jonathan Trott have averages in excess of 45; Prior averages in excess of 40. Each one of them have played top-class innings under pressure in the not too distant past. If there are better batsmen in England they have not made themselves obvious.
Yet England have failed to reach 400 for 17 Test innings - a run that extends back to Wellington in March - and several of their leading players - Cook, Trott and Prior in particular - are enduring runs of poor form too long for comfort and too long to be easily excused. It is no good living off past glories; Hobbs and Hammond have fine records, too. No-one would pick them now.
No expense has been spared in preparing this side. They have three batting coaches - Andy Flower, Mark Ramprakash and Graham Gooch - to work with here, they have brought in a couple of left-arm fast bowlers to face in the nets - Harry Gurney and Tymal Mills, who may well be the fastest bowler in England - to replicate Johnson's line of attack and they arrived in Australia four weeks before the Test series began. Some sides complete whole tours in that time.
The most galling aspect of this collapse was how easily England succumbed to Australia's plans. It took only two balls well angled across Joe Root to lure him into a horribly loose drive; it took only one spell of short bowling to have Trott, jumping around and playing almost exclusively to the on-side, caught behind. Pietersen flicked to the man placed for the stroke at midwicket and Cook, reaching outside off stump, soon nicked one angled across him. Wickets came far too easily for Australia.
But it would be simplistic to state that England were simply blown away by pace and bounce. Another nemesis also came back to haunt them: their weakness against spin bowling. On a day two pitch that remains utterly blameless, they made Nathan Lyon appear like Muralitharan on a dustbowl, with Bell and Prior departing to successive deliveries playing across balls that bounced and turned a little as if they had never seen an offspinner before.
Indeed, it might provoke England to reflect on the homogenised strips of lifeless sludge on which too much cricket is played in England. Rarely do developing players experience pitches that aid spin or pace in England, with far too much emphasis given to nagging seam and swing. It is a systemic failure that continues to hold back the international side. The pitch in Perth may be even quicker.
Equally, the ECB may reflect on the work permit regulations that they fought for and the central contract situation which has robbed the county game of many of the fastest bowlers. Even the absence of relatively obscure seamers - the likes of Johan van der Vath and Garnett Kruger - has limited the exposure of England players to the pace and aggression they can expect in international cricket. The gap between county and international cricket has grown considerably over the last couple of years.
Pace and bounce did not actually account for many of the top-order wickets. But it had left England rattled and it may well have resulted in their footwork being slower and their bats being less straight than they should have been. They looked, just as they had at Perth in 2010-11, more than a little shell-shocked.
History tells us that England can rescue themselves from this position. You only have to look at the Brisbane Test of 2010-11 or the Auckland Test of this year to see that. They are unbeaten for a year. But they have given themselves a mountain to climb here and, even if they do somehow salvage a draw - and with so much time left in the game, they may well need some help from the weather to do so - they will know that they have squandered a wonderful chance to take control of this series.