It is remarkable how quickly hope turns to disappointment.
Barely two weeks of playing time after England went into this series with dreams of glory, they are on the brink of relinquishing the Ashes. Instead of heading into the Christmas period full of excitement, there is every chance they will do so with disappointment the primary emotion and talk of transition in the air.
Nobody will be more disappointed than Joe Root. He arrived in Australia so full of excitement and enthusiasm. Accompanied by both his parents, partner and young son, he had a genuine sense that he could pull off a memorable success with his own batting one of England's key weapons.
Yet despite all his planning and hard work, Root has been unable to shape the series with the bat and unable to coax any magic from his side. Whereas he started the series in Brisbane with original fields and engaging plans, he has increasingly been reduced - like England captains before him - to throwing the ball in the direction of James Anderson and asking him to 'bowl dry' and wait for batsmen errors. Spending 150 overs in the field, game after game, will crush the spark out of any captain.
And, to rub salt in the wound, he had seen his opposite number, Steven Smith, excel with the bat. It was probably fitting that Smith produced the outstanding catch - he somehow clung on to a chance that ricocheted unpredictably from Tim Paine's gloves; truly the man's reaction time is freakish - to end Root's second innings on Saturday. As Root trudged off, the pain of regret and disappointment was etched all over his face.
There have been signs in this game that Root is starting to feel the burden of his role. That second-innings dismissal, driving at a wide one from Nathan Lyon - the spinner's first delivery - was uncharacteristically loose and followed a missed chance - he failed to react to an edge that flew past him at slip - and his public show of dissatisfaction with the decision to give Mark Stoneman out on review in the first innings. Root reacted to Aleem Dar's decision to overrule the on-field umpire's not out verdict by thumping the dressing room door in disgust. It was an unusual display of anger from a laid-back man.
But disappointment will do such things to a player. The chance to captain your country in an away Ashes series occurs rarely and very possibly only once. To see a lifetime of hope and several months of planning come to nothing is hard to take.
The positive interpretation of all this is that Root may be able to harness his pain and disappointment and use it as a motivating force next time. However, if he were to remain as captain in four years' time,especially after what is shaping up as such a heavy defeat, it would go massively against the grain of England's Ashes history. The last England captain to lead two away Ashes campaigns was JWHT Douglas, either side of the First World War in 1911-12 and 1920-21.
The more immediate concern must be whether England are compromising the effectiveness of their best player by asking him to lead the team. He is still averaging 50.27 in the role, however, and while he remains frustrated by his conversion rate (he has reached 50 47 times in Test cricket, but only converted 13 of those into centuries) this was only the second of his eight Tests as captain in which he has failed to reach a half-century. It's hard to sustain the argument that his form has been too badly compromised.
His dismissal here, however, did hint at a cluttered mind. He was trying to be positive and trying to stop Lyon from settling into that line and length that has troubled England all series. But as he walked off, he will have known that his last chance to influence the campaign with the bat probably went with him.
It was the second such dismissal he has suffered this series. After Australia exploited his propensity to fall over to the off side twice in Brisbane - he was leg before in both innings - he sliced an ambitious drive in the first innings at Adelaide before he was undone by a good ball (and a bit of uneven bounce) in the second. If he was a bit unfortunate in the first innings here - he was caught done the leg side - it might only have served as a reminder of how dearly he should have sold his wicket in the second.
He is walking a path familiar to many of his predecessors. To stand in the field for session after session, impotent in the face of the Australian batsmen, to see the hope of the thousands of travelling supporters - and the England fans have attended this series in remarkably numbers - turn to dust, to see your senior players fail to produce the contributions you know they must, and to be unable to make up for it with his own batting, has been a kind of torture for Root. It's not surprising he is showing one or two signs of the experience.
That failure of his senior players to contribute has added to Root's burden. If England were going to win this series, they needed Cook and Root - their two senior batsmen - to score heavily. As it is, Cook is averaging 13.83 and Root 29.33. It's nowhere near enough. And when he won the toss and decided to bowl first in Adelaide, he needed his senior seamers to exploit the conditions expertly. Instead they dropped short and any chance that might have existed was squandered.
There's been no lack of effort from anyone. But Lyon's pre-series comments about ending careers may yet prove prophetic. Certainly Stuart Broad, who here finished with the worst single-innings analysis of his Test career and hasn't taken a five-for for nearly two years, and Cook, who has not reached 40 in his last 10 Test innings (he has only reached 25 once) require strong performances in the final two Tests to quieten such talk. Broad, it might be noted, had a scan on his left knee before this Test. While the team management insist it is not a cause for concern and is not affecting his performance, they tend not to send players for scans unless there is some sort of issue.
And perhaps, in quiet moments, Root could be forgiven for wishing Ben Stokes had chosen to have an early night that fateful day in Bristol. It would be unfair on an excellent Australia performance to suggest it might have made all the difference, but there is no doubt that Root's most potent weapon was replaced by a burden that night.
In truth, Root wasn't dealt a handful of aces when he took this side to Australia. His squad lacks the quality spin or sharp pace that is usually required to prosper here and the batting has been betrayed as fragile. Perhaps in Brisbane, perhaps in Adelaide, perhaps here in Perth, he has had the same moment of realisation as all the England supporters that his side lacks the tools to hurt Australia. He will also know, however, that he and Cook and Moeen Ali and co have under-performed with the bat and it is that knowledge that may smart the longest. There is a gap between these sides, but it is not, perhaps, as large as it has looked in recent weeks.
It used to be said that a player doesn't recover from a disappointing tour of Australia. While there are several examples of players that have bucked that trend - Anderson and Root are obvious examples - it is certainly the case that such series tend to book-end careers. Root may need careful managing - including, perhaps, a break once this series is concluded - to ensure what remains a gem of a player is not dulled and drained by his disappointment.
Whatever happens from here, it seems England will persist with this group of players for the rest of the Ashes campaign. The Lions squad has, Mark Wood apart, now flown home, meaning there is no access to Keaton Jennings, Liam Livingstone, Dan Lawrence, Joe Clarke, Nick Gubbins et al who might have provided reinforcements in Melbourne or Sydney. As a result, the likes of Cook and Broad are going to be given every opportunity to show they still have what it takes to succeed at this level.