By all accounts Graeme Smith's announcement on Wednesday that he was stepping down as captain of South Africa's Twenty20 side, and would likewise relinquish the one-day captaincy after the World Cup, came as less of a surprise than one might expect.

After all, he is only 29 and has several years ahead of him yet, so on the face of it his decision to scale back his responsibilities may seem on the premature side.

But more than being a personal fancy, this is a crucial move for the Proteas as a team. As Smith himself pointed out at the press conference he has now been in charge for seven years, which is a long time by international standards.

The problem with this is not so much that South Africa need fresh ideas but that a power vacuum has developed under Smith. It's a fact that's reflected in the absence of stand-out candidates to replace him as captain of either limited-overs sides.

At the time of writing AB de Villiers was the tearaway leader in the Cricket365 poll asking who should take over the Twenty20 reins, yet de Villiers' experience of captaincy at any level is minimal. His main (only?) selling point for the role is that he's one of the few players under the age of 28 who can be considered a shoo-in for the side in all three formats.

Hashim Amla has been spoken about as a potential successor for Smith, but doubts remain as to whether a dressing room used to strong-headed, square-jawed captains would respond to such a softly-spoken character. It would be incredibly refreshing to see the country embrace a non-white, more cerebral leader, and he must remain favourite for the Test captaincy once Smith has gone, but for now Amla hasn't convinced that he deserves a starting place in the limited-overs side when he's not in blinding form. The coming season will tell us more.

For the moment the only candidate with a track record at international level is Johan Botha, and after his return to form in the Caribbean he must be the frontrunner for the Twenty20 job. Yet if the Proteas want to blood someone with one eye on the Test captaincy, can they be sure that Botha makes sense for the future?

All of which shows the depth of the potential malaise which has rightly been addressed before it could become a serious problem.

And of course it makes perfect sense for Smith, who bizarrely continues to have calls for his head by numerous members of the South African public despite the lack of obvious replacements.

The Twenty20 format is a draining one in which the likelihood of returns is low for captains when it comes to emotional fulfillment. It's bad enough that the odds are against any team winning the format's only real prize, the World Twenty20, given the number of teams and element of fortune involved, but when your detractors are only going to hit you with the 'it's only Twenty20' stick when you do win then it becomes a bet that's simply not worth taking.

These days Smith is a very reasonable man, but it appears that unless he wins every tournament and every Test series then the fickle among South Africa's fans will never forgive him. His chief crimes appear to be firstly that he was a brash 22-year-old captain, and secondly that he has bad timing. Smith's coming of age has won over some of the public, but it also coincided with a dip in South African fortunes so that some who previously took umbrage with his character now blamed him for poor results.

Some will never change their opinion of Smith but the man himself is clearly over that. Relinquishing power is another step in the process of evolving from the young captain who felt he always had everything to prove towards a more relaxed individual who is generally at peace with himself.