But the always-emotionally invested Microsoft head explained that it was his decision after he realized that the company's much-needed pattern break was being held up by himself.
"Maybe I'm an emblem of an old era, and I have to move on," he told the Wall Street Journal.
"As much as I love everything about what I'm doing, the best way for Microsoft to enter a new era is a new leader who will accelerate change."
Microsoft board not shocked
Ballmer's realization that Microsoft needed a reboot was obvious from all of the pressure his fellow executives disclosed in today's lengthy Journal piece.
"Hey, dude, let's get on with it," lead director John Thompson once told Ballmer in a conference call. "We're in suspended animation."
But the pressure from Microsoft's board is said to have been to always "go faster." The directors "didn't push Steve to step down," according to Thomson.
Not that it was a total stunner that Ballmer decided to exit either, with Microsoft board member Charles Noski commenting that he and other members weren't "surprised or shocked."
"While I would like to stay here a few more years," Ballmer told the board, "it doesn't make sense for me to start the transformation and for someone else to come in during the middle."
I've had the time of my life
But the board is now looking for its third CEO since its beginning in 1975, as it transitions from the Ballmer era into one filled with new toys in the hardware-dominated tech industry.
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