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The departure of Windows chief Steven Sinofsky, hard on the heels of the release of Windows 8, came as a shock, but not a surprise. But the important question is less what led to the departure of the talented but abrasive Sinofsky than how Microsoft uses its latest executive shuffle to move forward in a tech world it no longer dominates.

Microsoft is, in many ways, the anti-Apple. Unlike Apple’s tightly centralized, unified structure, Microsoft has long been a collection of fiefdoms. Although promoting Windows was the goal of just about every Microsoft product and effort, operating groups were often silos and turf was fiercely defended. Sinofsky, who had run the Office group, took over Windows after the Vista fiasco and proved his chops...