There were many reasons for the decline of Microsoft under Steve Ballmer, including, as I wrote this morning, its lack of focus and its habit of chasing trends rather than creating them. But one that’s not obvious to outsiders was the company’s employee evaluation system, known as “stack ranking.” The system—and its poisonous effects on Microsoft’s corporate culture—was best explained in an outstanding Vanity Fair feature by Kurt Eichenwald last year... So while Google was encouraging its employees to spend 20 percent of their time to work on ideas that excited them personally, Ballmer was inadvertently encouraging his to spend...