Retired Army Gen. Stanley A. McChrystal. Courtesy Photograph On his journey from battlefield general to Zoom-era grandparent, Stanley McChrystal has learned a thing or two about how plans go wrong. McChrystal commanded the U.S. operation in Afghanistan a decade ago and now sees the mission as a failure. “No way to sugarcoat that,” he says. These days, his priorities are easier to manage. When the grandkids walk into a work call, McChrystal politely—but quickly—wraps it up. Every engagement has its risks. MyCrystal retired as a four-star general in 2010 after a falling-out with President Obama. He now sits on the...