On Friday, Steve Ballmer announced that he would be retiring as CEO of Microsoft within the next 12 months. The stock market had a field day with the news, but the rest of us were were wondering why the longtime CEO was suddenly leaving right after announcing his intention to restructure Microsoft into a devices and services company.

According to sources speaking to All Things D, Ballmer’s sudden retirement wasn’t planned. In fact, the man himself referenced this in his internal letter sent to all Microsoft employees on Friday. In the letter, he said that his “original thoughts on timing would have had my retirement happen in the middle of our transformation to a devices and services company.” So, what changed? Those close to the company report that Ballmer and the board both agreed that it was time for him to leave.

Of course, people will tell you that Ballmer should have been out years ago. Last year, analysts were saying that Ballmer would be out of a job if Windows 8 failed. It’s a little unfair to call Windows 8 a complete failure, but it has failed to capture the kind of growth that both Windows 7 and Windows XP experienced. It doesn’t help that the company is sitting on $900 million worth of unsold Windows RT tablets. When you look at everything, it’s easy to see why the board would want to ditch Ballmer.

The interesting part about all of this, however, is how Bill Gates fits into all of this. For years, Ballmer and Gates were seen as the best of buds. They frequently appeared in Microsoft ads together, and Gates would stand behind the decisions Ballmer made. On Friday, that camaraderie wasn’t as apparent as Gates only said that he would be working with the board to find a replacement. All Things D says that employees took that as a sign that Gates was throwing Ballmer under the bus, but others say that Gates is just going along with the board’s decision even if he didn’t agree with it.

Whatever the case may be, Ballmer will be out of Microsoft within the next 12 months. He’ll have left behind a legacy unmatched in the tech world, even if that legacy isn’t exactly pristine.

[Image: Wikimedia Commons]