After five years as a top lieutenant, Gass is in the driver’s seat at Kohl’s at last. The no-frills department store chain is enjoying a rebirth fueled by some of Gass’s moves, such as lining up Under Armour as a partner and, more daringly, striking up a partnership with Amazon by giving that rival space at some stores. Gass was also key to rejiggering Kohl’s popular shopper loyalty program and pushing the chain to be an early mover in the activewear boom. The result was one of the best holiday seasons in 2017 of any retailer.