Here's a challenge for Australian cricket fans. Take a stab at the top five Sheffield Shield wicket-takers of the past decade. Thinking caps on? Right, make your mental list now.

How's it going? Remember, this goes back to March 24, 2006.

Want a clue? Only two of the five ever reached Test level.

Got your list?

Scroll down to see how you did.

Down a bit further.

If you're astute, you gained one point simply from seeing the photo at the top of this page.

The leading Sheffield Shield wicket-taker of the past decade is James Hopes, with 240 at 23.68.

Second on the list is Doug Bollinger, with 236 at 23.34.

Third comes Ben Hilfenhaus, with 223 at 29.32.

In equal fourth position is Luke Butterworth, with 221 at 24.61.

And sharing fourth spot and rounding out the top five is Michael Hogan, with 221 at 27.09.

Notice a theme? Four of the five on this list retired from Australian first-class cricket this season. Hopes and Hogan ended their Shield careers last week at the Gabba, where Hogan's Western Australia defeated Hopes' Queensland. Hilfenhaus bid a teary farewell last month. His Tasmania team-mate Butterworth called time in January. Bollinger is suddenly the last man standing, the old man of Shield bowling at 34.

This has been a season of change in state cricket. A number of new young batsmen have emerged: Matt Renshaw at Queensland with 738 Shield runs at 43.41, his team-mate Sam Heazlett with 649 at 40.56, Victoria's Travis Dean with 642 at 40.12, Jake Lehmann at South Australia with 609 at 50.75. Other batsmen, less new but still young, have continued to take strides this season: Travis Head, Cameron Bancroft and Kurtis Patterson among them.

There are some impressive young bowlers emerging too. Joel Paris took 35 wickets for Western Australia at 19.57 and debuted in ODIs; South Australia's Daniel Worrall claimed 37 at 26.86; Chris Tremain took 32 for Victoria at 19.68; Queensland allrounder Jack Wildermuth picked up 25 at 22.96 - and scored his maiden hundred. Jason Behrendorff and Billy Stanlake were affected by injuries but have great expectations on them.

All of those men, the batsmen and the bowlers, are aged 25 or under. But after the retirements of Chris Rogers and David Hussey last year, the rest of the Shield's older batting generation remains largely in place. The same cannot now be said of the bowlers. The collective loss of Hopes, Hogan, Hilfenhaus and Butterworth takes nearly 1000 career wickets out of the Sheffield Shield competition since the start of this year.

And so it seems fitting to look back on the careers of these four retirees, all giants of Sheffield Shield cricket, who were understated and often underappreciated. Hilfenhaus was the only one who won a baggy green. Hopes played ODIs and T20s for Australia but was never seriously considered for Test cricket. Hogan arrived late, already 28 when he debuted. And Butterworth was one of the most effective yet undervalued Shield players of his generation.

Let's start with Hopes, the longest-serving member of our quartet. There are those who will remember Hopes mostly as a one-day international cricketer, an allrounder who was something of a fixture in Australia's side from 2006 to 2010. A removable fixture, though, if that is not too much of an oxymoron. Despite playing 84 ODIs, he was left out of the 2007 World Cup squad and was ditched before the 2011 World Cup.

Hopes was the kind of player any captain would love to have in the side: adaptable and hard-working. He opened the batting a handful of times in ODIs, though he was more typically in at No. 7 or 8. As a bowler, what he lacked in pace he made up for in other ways. At his peak, in late 2009, he was No. 2 on the ICC's rankings for ODI allrounders, and No. 8 on the bowling rankings. A year later he was axed for good.

Everything about Hopes was unfashionable, even down to his haircut. But fashions come and go. Hopes didn't - at state level, at least. His Sheffield Shield debut came in 2001, a shared debut with Mitchell Johnson. Hopes not only stuck around until 2016, when he was 37, but continued to be one of the competition's most effective bowlers. Over the past three years he has taken 102 wickets, more than any other Shield bowler.

His tally of 301 first-class wickets at 26.66 is impressive, but what is especially notable is that they came almost entirely for Queensland. Only five of those wickets came for anyone else, and that was Australia A. Not for Hopes the idea of switching states, or seeking a handsome county deal. He was a Bull through and through, and as captain led Queensland to back-to-back Shield finals in 2012 and 2013, winning one.

"I was never a person who walked into a contract meeting and started negotiating," Hopes told the Courier-Mail in an interview last week. "Whatever was put in front of me I signed and told them I would see them at pre-season... I have never felt comfortable being in the spotlight. I would rather be that hard-working person in the background."

That he certainly was. As Hopes said in the hours after his final Shield appearance last week: "I had to train my ring off. Guys like Andy Flintoff, who can genuinely bat at six and take the new ball, they are rare. I strived my whole career to be in that bracket."

The final hours of Hopes' Shield career were shared with Hogan, a man who could wander the street in almost any Australian city without being recognised. And yet this is a bowler with more than 400 first-class wickets, and the leading Shield wicket-taker of the past five years. You have to wonder what Hogan might have achieved had he found a way into state cricket earlier.

Hogan played grade cricket in Sydney in his mid-20s before returning to his home city of Newcastle, and that could easily have been where his cricket career was played out. But he had another crack with Northern District in Sydney in 2008-09, and that led to an unexpected phone call from Western Australia coach Tom Moody, inviting him to a trial in Perth. "Within the space of four days, I'd signed my first contract," Hogan told Perth's Sunday Times this month.

He made his Shield debut at 28, and has never looked back. Now 34, Hogan retires from Australian first-class cricket at No. 8 on the list of Shield wicket-takers for Western Australia, having moved one wicket ahead of Moody on the side's all-time Shield list. However, Hogan will add to his first-class tally, with three years yet to run on his contract with Glamorgan, where he plays as a local thanks to British ancestry through his mother.

More recognisable than Hogan is Hilfenhaus, largely due to the fact that he played 27 Tests. But you never got the feeling that fame sat all that comfortably with Hilfenhaus. The son of a plumber from Ulverstone in northern Tasmania, Hilfenhaus worked as a labourer for a bricklayer when he first moved to Hobart. Ahead of his Test debut in South Africa in 2009, he told ESPNcricinfo: "I still see myself as pretty laid-back, I don't like to over-analyse anything".

His greatest weapon was swing, and at his best he swung the ball late enough to cause chaos for batsmen. But his career tally of 99 Test wickets at 28.50 suggests he was something of a nearly man at international level, though injuries played their part in curtailing his career. Upon Hilfenhaus' retirement, Tasmania coach Dan Marsh declared him "our best ever Tasmanian-produced bowler and certainly one of the finest ever cricketers that Tasmania has produced".

No arguments there. But in his own way, Butterworth was also one of Tasmania's finest. When he retired in January at the age of 32, it was with little fanfare, given that he had not played a Shield game in nearly a year due in part to a persistent back injury. But he is a man who deserves to have his feats recognised.

On stats alone - 223 first-class wickets at 24.68 and 2762 runs at 27.89 - you would think Butterworth would at some point have been considered for a Test tour. Not picked, necessarily, for Australia have had plenty of good fast bowlers and allrounders in recent years, but at least considered. But not only did he never play for Australia, he only ever played one first-class game for Australia A.

Butterworth was a big-game player. He will go down in history as Man of the Match in the 2006-07 Pura Cup final, a historic moment as Tasmania won the state title for the first time. It was just Butterworth's fifth first-class game, yet he showed remarkable maturity to score 66 and 106, as well as collecting 4 for 33 in the first innings. Then in the 2010-11 final he made 88 in a Tasmania win, and scored 86 in their final win in 2012-13.

All the while, his bowling was consistently effective, hence his place on this list of the top five wicket-takers of the past decade. In 2010-11, he was equal top of the Shield wicket tally with 45; Trent Copeland shared top spot and won a baggy green on the tour of Sri Lanka later that year. All Butterworth got out of it was an Australia A tour of Zimbabwe.

So there you have it. Hopes, Hogan, Hilfenhaus, Butterworth, all gone by the end of this Sheffield Shield season, but all deserving of having their achievements recognised. Nearly 1000 Shield wickets between them. It is indeed a changing of the guard.

And then there was one. And then there was Doug.