It's been a week since I brought up Facebook (META -0.52%) COO Sheryl Sandberg as a rock star candidate to be Microsoft's (MSFT 0.37%) next CEO, and apparently I'm not alone. 

Social wagering website Ladbrokes has gone from making the Lean In author a 25-to-1 long shot on Friday to a viable 5-to-1 bet as of last night.

Why is Sandberg's name starting to gain traction? Why would she leave Facebook?  

Sandberg's been selling Facebook shares lately. She unloaded more than $95 million of the social networking giant through a pair of transactions last month alone. Insider selling obviously isn't a prelude to a resignation, but it's clearly not an incentive to stick around.

Yes, she's diversifying. Yes, she's entitled. Yes, she's been selling for a lot longer than Steve Ballmer has had cold feet. However, this is the way chatter gets started. I threw her name out there on a lark seven days ago, and now she's second only to the uninspiring choice of Stephen Elop for folks putting their money where their mouths are.

The biggest reason why Sandberg's name is so tantalizing is because she has Google (GOOGL 0.55%) pedigree papers. AOL's (NYSE: AOL) Tim Armstrong and Yahoo!'s (NASDAQ: YHOO) Marissa Mayer were plucked from Google's executive ranks, and both of those investments have risen nicely in their tenure. Sandberg is even more compelling than Armstrong at Yahoo! and Mayer at Yahoo! because she also went on to succeed at Facebook, too.

A big knock on Sandberg will be that she's not a software person. She's a Harvard MBA with an economics background. Her strength is monetizing websites, as she headed up Google's global online sales and operations before being poached by Zuckerberg to transform Facebook into a sustainable business.

However, Microsoft made it a point to emphasize that it's no longer a software company. It wants to become a products and services juggernaut. Sandberg may not exactly be Yahoo!'s Mayer on the products end -- and she's not a perfect fit on the services front -- but she's more than qualified to send a message to the world that Microsoft is making a clean break from the past. 

At the very least, Sandberg will turn Microsoft's money-losing online operations around. At best, she will be a magnet to bring in the new breed of executives that will help reshape Microsoft into the reborn Wall Street darling that it will become under her watch. 

Just a name can excite investors. Yahoo! shares have nearly doubled in Mayer's brief tenure, and that's with revenue still showing no signs of life. AOL has run into a few bumps during Armstrong's longer run, but the market's still giving him the benefit of the doubt since the shares have appreciated nicely in his time at the helm.

Sandberg is a bigger name than Mayer and Armstrong. She's tasted success at the two most prolific online companies on the planet. One of them is Microsoft's biggest enemy. The other is an ally. This year's publication of  Lean In: Women, Work, and the Will to Lead has become a Silicon Valley anthem of feminism, but its very premise -- that women need to lean in when opportunities present themselves in meetings instead of leaning back -- may also explain why she would take the position if it's offered.

CEO at Microsoft? You can't lean in any more than that.