In what might be seen as the last major Sinofsky-era defection from a position at one of Microsoft's core businesses, Julie Larson-Green revealed to employees that she will be leaving the firm's Devices and Studios group to start a new role at the company. A long-time top lieutenant to Steven Sinofsky, Larson-Green will now start her third new job in the 15 months since Sinofsky suddenly and mysteriously left Microsoft.

Larson-Green follows at least one other Sinofsky acolyte, former Windows user experience lead Jensen Harris, to Microsoft's Applications and Services Group (ASG), itself a mysterious amalgamation of parts of the firm that were scattered during the recent reorganization. Depending on whom you ask at the company, ASG is either Microsoft's version of Siberia or a startup-like organization within the firm that will drive future cross-product innovations.

Larson-Green put a positive spin on the change in an email message to her current direct reports in the Devices and Studios group.

"I've accepted a new challenge, leading the My Life & Work team in ASG and serving as the Chief Experience Officer (CXO)," she wrote. "As hard as it is for me to leave Devices & Studios, I'm thrilled about this opportunity ... I'm looking forward to developing the Digital Life & Digital Work Experience Substrate that powers modern digital experiences regardless of device, as well as working across ASG to strengthen customer experiences."

Larson-Green's fate in Devices and Studios has been a bit unclear since Microsoft announced its plans to acquire the devices and services businesses at Nokia along with its then-CEO, Stephen Elop. When the firm announced these plans, it said that Elop would run the Devices and Studios business and that Larson-Green would in effect be demoted to report to him.

Larson-Green's email to employees doesn't hint at the impetus for her move, and it's possible that this was instigated by new CEO Satya Nadella, Mr. Elop, or by her own desire for change. She rose to prominence under Steven Sinofsky during their time in the Office business, and joined him as his effective number two when Sinofsky unofficially took over Windows in 2007.

Almost immediately after the disastrous release of Windows 8, Sinofsky surprised everyone—including Larson-Green, as it turns out—and suddenly left Microsoft. In the wake of his exit, virtually every member of his core leadership team has either left Microsoft as well or moved on to other parts of the company.

Larson-Green and Tami Reller were briefly assigned co-control of the group at that time, but when Microsoft underwent a dramatic "One Microsoft" reorganization in 2013, Larson-Green moved on to the Devices and Studios group, where she oversees Xbox, Surface, hardware accessories and game development; along with Windows 7 and 8, Surface was one of Sinofsky's key projects at Microsoft. She will remain in this role until Mr. Elop and over 30,000 Nokia employees join the company when the Nokia acquisition is finalized.