"They would want to plan for what happens to the other people who were being considered, including if they decided to then leave," said Rubin.
Jumping ship may be a tough decision for some execs: In late September, Microsoft revealed it had handed out millions in stock grants to eight men and women to ensure "continuity of key leaders during the transition to a new chief executive officer." At the time, the grants were worth between $1.6 million and $19.9 million each, with COO Kevin Turner scoring the top award.
However, several of the widely-cited internal prospects, including Nadella and Tony Bates, the CEO of Skype before it was acquired by Microsoft and now the head of the Business Development and Evangelism group, were not among the eight.
"And if [the leading candidate] is external, say Alan Mulally [CEO of Ford Motor], there are things that person may have to do at their current company before they could accept," said Rubin.
Analysts and pundits who bet that Microsoft would act this year, not next, based their opinions in part on Ballmer's mistakes -- being unable to successfully move Microsoft from the desktop to mobile was at the top of their lists -- and a need for quick decisions to get the company executing the strategy Ballmer and the board have laid out to transition to a devices and services company.
While a wait of a month or more won't be disastrous, Rubin noted even after the selection is announced, a period of uncertainty will prevail. It's typical for any new chief executive to take between one to three months to assess the situation and present their ideas to the board, said Rubin. Only then would the company and its employees get new marching orders.
"If a month or two is going to make a difference, it's certainly worth spending the time," Rubin concluded. "And if they're closing on the right candidate, there may be some road blocks that need to be cleared first."
Sign up for CIO Asia eNewsletters.