There is precisely one reason Microsoft's (NASDAQ:MSFT) Steve Ballmer had to go: speed. Ballmer simply wasn't moving fast enough to accommodate the rapidly evolving competitive landscape, judging by a recent series of interviews with The Wall Street Journal. Ballmer certainly grew revenue and operating profits in Microsoft's core software and enterprise businesses during his long tenure, but he also undeniably missed out on major opportunities such as mobile, online services, and search advertising.

Microsoft's board wasn't pressuring Ballmer to step down explicitly, but they were pressuring him to accelerate his strategic plans. Over the past year, Ballmer has restructured Microsoft's organizational hierarchy in preparation of transitioning toward devices and services. Ultimately, Ballmer himself eventually realized that he wasn't the right man for the job, and that some fresh blood was needed to carry out his vision.

In this segment of Tech Teardown, Erin Kennedy discusses the details of Microsoft's departing CEO with Evan Niu, CFA, our tech and telecom bureau chief.