Why Cynthia, because late last week Cynthia Carroll became the first of the current generation of the mining industry’s top leaders to fall off the wall of power, quitting her job as chief executive of Anglo American, but leaving behind delicious unanswered questions, such as:

Did she fall or was she pushed?

If Cynthia can fall so easily, who’s next? And

Will the replacement bottles, sorry, chief executives, bring big changes to global mining?

On the matter of fall versus push, there seems little doubt that institutional investors in the South African mega-miner believed that Cynthia had reached her use-by date.

Officially, the first woman to head a global miner is standing down in an orderly move, allowing time for a successor to be chosen.

Unofficially, investors have been urging her to go because of the poor performance of Anglo American during her six years in the job.

Cost blow-outs on a big iron ore project, plus a bruising fight with the government of Chile, plus paying too much for control of the big diamond producer and dealer De Beers have damaged Cynthia’s credentials.

But the final straw, as far as investors were concerned, was a 55% fall in first-half profits, compounding an already poor financial run.

Since October 2006, when Carroll was appointed, Anglo American has delivered a negative total shareholder return of 13%, compared with BHP Billiton’s plus 127% and Rio Tinto’s 51%.

Defenders of Carroll’s performance include her chairman Sir John Parker, who praised the way she boosted the company’s safety performance and restored its relations with the South African government.

Admirable as her achievements might be, the reality in the financial world is that safety and government relations are well down on what investors want - profits, dividends and a rising share price.

But what’s really interesting is that change at the top of one company often has a habit of becoming a trend for a number of reasons, including:

The changed outlook for mining, which has flipped from expansion driven to cost-cut driven.

Different economic conditions generally require a different management approach, and

What’s called the “it’s time” factor.

Add those factors together and you start to see that the directors of all major mining companies will be looking closely over the next six-to-12-months at the question of future leadership.

If asked to name the next bottle, sorry, chief executive to fall, Dryblower would start singing farewell to Xstrata’s Mick Davis but since Davis has already flagged his intention to leave after the merger with Glencore is complete that’s a bit of a no-brainer.

After Davis, the heat will be on Tom Albanese at Rio Tinto. A talented and pleasant man, Albanese has been heavily criticised for his role in the disastrous $US40 billion acquisition of the Alcan aluminium business, though it could be another issue which is used as an excuse to replace him – excessive reliance on a single division; iron ore.

Under Albanese, Rio Tinto has become what a previous boss of the firm Leigh Clifford scathingly called a “one-trick pony”, with close to 80% of the company’s profits coming from that single division.

Marius Kloppers at BHP Billiton is the fourth green bottle teetering on the wall, and while he may see out another year or so his record is suffering from the same blots that affect all chief executives after a long period in power.

The charge into US shale gas was Kloppers’ biggest mistake, but failing to acquire Potash Corporation in Canada was almost as bad, as was messing up the Olympic Dam expansion.

Of all the issues underpinning an expectation of wholesale chief executive change among the mega-miners it is a combination of the “it’s time” factor and the outlook change from growth to cost-cutting.

All four chief executives were appointed at a time of high commodity demand, rising prices and grand expansion plans. They were probably the best people in those times.

They are probably not the best people for a time of penny-pinching cost cuts, project deferrals, staff retrenchments and delicate dealings with governments annoyed by falling levels of investment which are hitting their tax revenues.

“Four green bottles standing on the wall and if one green bottle should accidentally fall" … etc etc etc.

This article first appeared in ILN 's sister publication MiningNews.net.