Bob Mullaney, an executive with more than two decades of experience in the footwear sector, has been appointed to the new position of president and chief operating officer of ShoeBuy, the Boston-based online shoe retailer, reporting to its chief executive, Mike Sorabella. Most recently, Mullaney served as president of Rockport for the Americas. He was part of the executive team that facilitated the sale of the company by the Adidas Group to a new entity established by New Balance and a Boston-based investment firm, Berkshire Partners. Mullaney previously worked at the former Brown Shoe Company, Vida Group and Stride Rite Corporation.