Steve Ballmer is a sales guy at heart, and it's why he's been able to survive a decade of middling stock performance and strategic missteps: He must have close connections to Microsoft's largest enterprise customers, and were he to be fired, it would be an invitation for those customers to reevaluate their commitment to Microsoft's platforms.

When he walks into a big customer's boardroom, he must be furious every time he sees some C-level using an iOS or Android device. He knows that if he can't sell "Windows everywhere" to these users, he's doomed to keep reading headlines about 5,000-user iPad-based IT projects and the "post-PC era".

He didn't need to wait to see how the market would respond to Windows 8 and devices like the Surface. These users could tell him immediately, perhaps even before the product launched, and I would guess that their feedback was discouraging. If at the same time their IT departments were making noise about sticking with XP or 7, that would have been the last nail in Sinofsky's coffin.