Show up at a Rick Perry campaign event, whether a book signing in New Orleans, a prayer rally in Houston or a speech to enthusiastic Republican faithful in South Carolina, and you may notice a hulking, gray-haired man standing on the fringes of the crowd. He rarely gives interviews these days and is not yet well-known outside political circles. Yet, Dave Carney is, without question, the most important person in Perry's presidential quest outside of the candidate himself. Almost every presidential election cycle, the spotlight illuminates a campaign guru whose tactical acumen seemingly propels his client to heights unreachable alone....