When Zac Posen, the designer of stunty Met Gala frocks and meticulously constructed ball gowns, was appointed creative director of Gap Inc. in February—a job that ostensibly put him in charge of the design, merchandising, and marketing of Old Navy, one of the largest and unsexiest clothing brands in the world—few people thought he would actually show up for his new remit. No matter how invaluable his advice might be to Gap Inc. C.E.O. Richard Dickson, red carpet guys like Posen don’t typically engage on a day-to-day basis, and they certainly don’t spend their days hovering around the office Keurig machine. They go to the Vanity Fair party and get photographed standing on the bullseye in a Banana Republic suit, as Posen did this past Oscars season.