Kevin Rudd was at the center of attention at the UN this week, mainly because he wasn't there. Nine candidates to be the next UN secretary-general addressed the General Assembly between Tuesday and Thursday. Star attractions included two former prime ministers: Antonio Guterres of Portugal and Helen Clark of New Zealand. But there was much muttering in the margins of the UN about prospective candidates who have yet to enter the race, including Rudd.

The last week's hearings were meant to be an unprecedented non-event (not a contradiction in terms in New York diplomacy). The UN has never held formal sessions with potential secretary-generals before. In the past, the five permanent members of the Security Council largely stitched things up in private, with the US running the show 90% of the time. While a coalition of small states and NGOs had successfully pushed for a bit more transparency this time, a lot of observers were sceptical about the results. I for one had predicted the whole thing would be dull, with diplomats being diplomatic and the candidates trying to avoid any controversy.

Kevin Rudd may have taken a similar view. It is no secret that he has been eyeing Ban Ki-moon's job for some time. He enjoys a well-established international profile. By contrast, a lot of the nine declared candidates are strictly local heroes in their home countries. All have held high office at home (foreign minister, premier or head of state) but quite a few come from small Eastern European countries that even foreign policy mavens tend to overlook. Did you know that Igor Luksic was former prime minister of Montenegro, for example? Nope? UN diplomats now do, because he was the first candidate up in front of them at 9am on Tuesday. He did perfectly fine.

Rudd may have hoped that he could sit out this round of UN blathering, and then enter the race at a later stage as a bigger-name candidate after the Balkan minnows had gone home. A number of other serious potential nominees, such as Argentinian Foreign Minister Susana Malcorra, are also said to be sitting back to watch events.

But holding back has had some unexpected disadvantages. This week's sessions were unexpectedly lively, at least by the moribund standards of UN debates. Some diplomats posed repetitive and tedious questions to the candidates about management issues and fascinating topics such as the UN's promotion of sports. But others raised more serious issues. The US, for example, repeatedly asked what candidates will do bolster UN peacekeeping, which costs US$8 billion a year. Ukraine needled Irina Bokova, the Bulgarian head of UNESCO who is rumored to be a favorite candidate of Russia, by asking about her views on Crimea. She ducked that.

More importantly, quite a few candidates found ways to capture attention. Portugal's Guterres, who ran the UN refugee agency after leaving domestic politics, was witty. He promised to rid the UN of acronyms, which is a bit like pledging to rid Australia of kangaroos – it would destroy its global brand. Vuk Jeremic, a former Serbian foreign minister, presented diplomats with an 80-page action plan on issues from climate change to African peacekeeping. And then there was Helen Clark.

Clark has been an obvious candidate, like Rudd, for a long time. But she also seemed to be hanging back. But she upset expectations by leaping into the race just before the hearings, and was immediately anointed one of the front-runners. Suddenly observers were asking why Rudd had not decided to enter the race at this stage too.

None of this is decisive. The rules of the race are still loose. Rudd can enter any time he likes, and there will surely be another round of hearings (or more) with him, Malcorra and other late entrants. While diplomats are currently rather buzzed by the last week's hearings, the adrenaline will fade, and they will need another fix. By the end of the year, this week's discussions may be forgotten. And at the end of the day, the General Assembly doesn't have much sway over who gets to run the UN anyway – the choice still lies, for good or ill, in the hands of the five permanent members of the Security Council. Russia in particular distrusts all the transparency.

But Kevin Rudd should not hang back too long. UN watchers have long thought he'd be an exciting candidate, with vigor, great contacts and big ideas. But for now, people are going to talk about Guterres' jokes or Jeremic's hefty policy platform – while Rudd is notable by his absence. Politics is all about timing. Just occasionally, you can wait too long to jump into a race and find it's somehow run away from you.

Photo courtesy of Flickr user United Nations Photo.