The spectacle of Australia’s longest-serving Premier announcing his retirement after a tap on the shoulder from a little-known union official has excited much comparison with Labor’s recent leadership shenanigans federally and in New South Wales. But from another perspective, Mike Rann’s premiership and the manner of its ending marks a significant departure from the party’s recent practice.

The arrival of the Rann government in March 2002 completed an ALP clean sweep of the nation’s six state governments, a process that began when Bob Carr came to office in New South Wales in 1995. His other counterparts at the time were Peter Beattie, Premier of Queensland since June 1998; Jim Bacon, who came to power in Tasmania the following September; Steve Bracks, Premier of Victoria since October 1999; and Geoff Gallop, elected in Western Australia a year before Rann.

By September 2007, all of these leaders had gone — and unlike Rann, not a single one had been pushed. Carr, Bracks and Beattie left entirely on their own terms in August 2005, July 2007 and September 2007 respectively; Gallop resigned in January 2006 after announcing he was struggling with depression; and Bacon quit the previous June due to a battle with lung cancer, which would claim his life three months later.

By very stark contrast, Rann has lingered well beyond his use-by date, and while the particular manner of his execution might be questioned, it seems a little unfair to tar its architects with the brush of Sussex Street. Rann has led the state for 9½ years and the party for nearly 17, and despite strong performances in 1997 (when Labor nearly returned to power one term after the 1993 massacre) and 2006 (when his government was handsomely re-elected after a successful first term), not even the most charitable assessment of his electoral record can argue that he deserved more time.

The chart below benchmarks Rann against other mainland Labor state governments by plotting their two-party election results against their length of time in office. This shows four of the five with remarkably similar trajectories for their first terms, before South Australia breaks away with a much sharper decline going into the subsequent election (Western Australia, of course, is an even odder man out; more on that shortly).

However, a mitigating circumstance becomes apparent if we work off real time rather than each government’s year-zero. The chart below suggests either that the election of the Rudd government in November 2007 was a watershed event (the occasion of which is crudely marked by the vertical line), or that it happened to coincide with an acceleration in the various state governments’ natural rates of decay.

While it may immediately appear that a general decline is already evident in 2007, this is partly because sharp downward trajectories for Western Australia and South Australia are locked in by the post-Rudd elections of 2008 and 2010. It is true that the Queensland, Victorian and NSW governments were already heading south on the back of their September 2006, November 2006 and March 2007 results, but in each case the tempo quickened after November 2007 (calamitously so in the case of New South Wales).

The point is further emphasised by the fact that the “newer” governments of Western Australia and South Australia are the two that record premature declines in the first chart, as the federal anchor was weighing them down earlier in the piece. Rann can thus claim some sort of an alibi for falling short of his counterparts in the three biggest states.

However, it’s instructive to compare Rann’s trajectory with that of Geoff Gallop and Alan Carpenter, ignoring the temptation to regard WA as an exceptional case. Gallop’s government came to office on the back of the highest two-party vote of any of the five incoming governments under observation, but it uniquely flatlined when first up for re-election in 2005. A distorting factor here was the free kick Labor had received from One Nation preferences in 2001: Gallop did receive a fillip in 2005 on the primary vote, which was up from 37.3% to 41.9% (the only time WA Labor has topped 40% at a state or federal election since 1987). Nonetheless, the 2005 result undeniably stands out from the crowd, the conventional explanation for which is a creeping conservatism that has also seen Western Australia weaken for Labor federally.

That being so, it is notable that Rann’s result in 2010 was hardly better than what Alan Carpenter managed on far less friendly electoral turf for Labor in 2008, notwithstanding that Rann’s government did actually cling to office. This might have something to do with the fact that the WA Liberals had changed leaders on the eve of their campaign, or with the decline in federal Labor’s fortunes in the 16 months that separated the two elections. However, there seems equally strong grounds to blame Labor’s leadership issues in South Australia —  namely the encumbrance of the Michelle Chantelois episode, and well-founded scepticism as to whether Rann would see out the ensuing term.

Recent polling strengthens the argument that Rann has become a heavier weight for Labor than he has had a right to be. Not only has he recorded consistently big deficits against Liberal leader Isobel Redmond as preferred premier, he also trailed Jay Weatherill by 40% to 27% in a recent poll conducted by The Sunday Mail. Notwithstanding the bad reputation that leadership changes have acquired of late, Labor’s caucus and factional bigwigs were entitled to conclude that Rann’s extended victory lap had become an indulgence the government could no longer afford.