"I used to be with it, but then they changed what it was. Now what I'm with isn't it, and what's it seems weird and scary to me, and it'll happen to you, too."

Many a cricketer at the mercy of selection whims will find something empathetic in Grandpa Simpson's line about the passing of time and age. Few, though, will find it ringing more truly than Alex Carey, who in the space of less than a year has found himself moving from the status of "emerging talent and leader" to that of "ageing pro battling to hold his place in the national team".

Some players, like the national team coach Justin Langer, spend virtually their entire careers feeling like the latter, whereas Shaun and Mitchell Marsh each retained the former tag for more than a decade. The major variable tends to be the emergence of others to challenge for the same spot, and in Carey's case his probable usurper is no longer a distant dot in the rearview mirror.

An exceptional rearguard century in the company of Glenn Maxwell to win Australia the ODI series against England in Manchester not only broke a sequence of slim scores in national colours that had begun in the wake of Carey's breakout World Cup performances, but also held back the voices advocating ever more bullishly for the claims of the 23-year-old Josh Philippe. As a performance it carried more than a passing resemblance to Ian Healy's big Test century against West Indies at the Gabba in November 1996 when Adam Gilchrist was fast closing on his place.

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From there, Healy was able to retain his spot for another three successful years, winning two more Ashes series away and at home to ensure Australia retained global supremacy in Tests until he left the stage to Gilchrist in 1999, by which time the younger man had just turned 28 and won an ODI World Cup himself. Carey is now of a similar vintage.

It's more or less exactly a year since the selection chairman Trevor Hohns had spoken glowingly of Carey, his leadership qualities and the panel's desire to see him promoted to the captaincy of South Australia in place of Travis Head. Carey had been promoted to co-vice-captaincy of Australia's T20 team, and was also Tim Paine's wicketkeeping, if not leadership, understudy in Test matches.

That Carey was 28 years old did not appear to be much of an issue for the selectors at the time, and it was often noted that the years he had lost in pursuing a football career - he was inaugural captain of the Greater Western Sydney Giants before the AFL's 18th club formally entered the league - had provided him with an array of life experience useful to aiding the progress of teams. Fatherhood, too, was seen as a useful exemplar of Carey's status as an adult among the frequently arrested development of cricketers.

What happened then, to change the arc of Carey's tale? First, the Test captain Paine's performances improved after some shaky moments during the Ashes, as he and the selectors gained greater clarity about how much further he will go. It seems now that Paine will lead at least until the end of the nominal World Test Championship cycle in July 2021, and more than likely carry on until the end of the home Ashes series in January 2022, by which time he will be 37 years old.

Secondly, Philippe maintained his upward curve as, alongside his fellow West Australian product Cameron Green, two of the most promising young batting talents in the country. Philippe delivered impressive consistency for the title-winning Sydney Sixers in the BBL, while also scoring his runs at a notably faster tempo than Carey for the Adelaide Strikers. And though Carey's Sheffield Shield returns for South Australia were comfortably better than Philippe's, it was also evident that international teams were homing in on the left-hander's areas of weakness after getting a sighter during the World Cup.

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When Covid-19 intervened in March, the wheels were set in motion for another major change to Australia's schedule, the postponement of the 2020 T20 World Cup to 2022, with the next edition of the event to instead be held in India in late 2021. The selectors suddenly had a lot more time to consider their choices for wicketkeeper-batsman.

This all meant that Carey didn't go to England for his first assignment of the 2020-21 season with complete certainty around his place in the team. Tellingly, he had lost his share of the vice-captaincy, and in Philippe faced a younger competitor with a more outwardly brash attitude than the humility noted by virtually anyone to spend time around Carey.

All these dynamics influenced the shape of the Australian squad, but also made other team-mates aware of the fact that "Kez", as he is affectionately known, might not be around for as long as had previously been the case. This much was underlined when Gilchrist, styled as a mentor to Carey in 2019, had spoken up about Philippe: "I reckon a guy who, in time, could very well be the solution, whether it's going out at No.1 or 2 or getting a chance in that middle order, is Josh Philippe.

"Very exciting young talent, still learning his craft, about himself and what his capabilities are, and of course match situations. But the quicker you get them exposed to the top level with that uninhibited approach, he can maybe catch a few teams off guard."

Very quickly, Carey was being spoken about as the shaky incumbent rather than the coming man, a position numerous others in the team will have empathised with given their own histories. There was certainly a great deal of warmth in Maxwell's voice when he spoke in the aftermath of his Old Trafford stand with Carey, as they provided an ideal contrast of approaches to win a game that had appeared almost certainly lost.

"Batting with Alex Carey out there, seeing him get his first ODI hundred is pretty special, knowing how hard he's worked, he's such a great person and one of the great guys to be around, I see him every day, he makes me smile and we always have a laugh together," Maxwell said. "To see him get the rewards at the other end was extremely special, and to top off and beat the No. 1 team on their own soil was even more special."

Competition for places is something Langer has been hoping to see for quite some time, and there was plenty of glee in his voice as he talked about seeing numerous incumbents being pushed to greater achievements by those challenging them.

"Another thing I'm loving is that there's a real competition for spots. And that is exciting for me," he said this week. "In all forms, there's great competition. And there's great opportunities through the IPL leading up to the white-ball summer [and] Sheffield Shield cricket. I love that in Australian cricket."

Carey remains a more likely understudy to Paine should the captain suffer any misfortune with his problematic right index finger this summer, but it now appears that his place will be primarily as a link man between eras. Philippe, unveiled as the No. 6 for Royal Challengers Bangalore in the IPL while Carey is understudy to Rishabh Pant for Delhi Capitals, looks increasingly like the long-term gloveman of the future.

That is, of course, until another contender shows up to challenge. At that point, it will be Philippe hearing Grandpa Simpson's warning. "It'll happen to you, too."