Ballmer Departure From Microsoft Was More Sudden Than Portrayed - Kara Swisher - News - AllThingsD

Additional perspectives on Ballmer's exit

"Instead, sources said Ballmer’s timeline had been moved up drastically — first by him and then the nine-member board, including his longtime partner and Microsoft co-founder and chairman Bill Gates — after all agreed that it was best if he left sooner than later.
That was due to a number of increasingly problematic issues on the immediate horizon — including a potentially nasty proxy fight, continued business performance declines and, perhaps most of all, that Ballmer’s leadership was becoming a very obvious lightning rod."

Ballmer Departure From Microsoft Was More Sudden Than Portrayed - Kara Swisher - News - AllThingsD