WITH HER NEXT ALBUM, 2012’S Red, Taylor Swift aimed, she said, to go outside her comfort zone, collaborating with new people (Ed Sheeran and Snow Patrol’s Gary Lightbody) and exploring new sounds. That meant leaving behind some of her old sound, and the effort alienated parts of the country music establishment, which had twice named her Country Entertainer of the Year. The first single, “We Are Never Ever Getting Back Together,” coproduced by Max Martin and Shellback (then best known for working with Britney Spears), had a modest debut at No. 13 on the country chart, based on radio play. “Country radio has been a little taken aback,” admitted Scott Borchetta, head of Swift’s then label, Big Machine. Only after Billboard started including streaming sales did the song soar to…