From a Sports Illustrated article on the story of Under Armour, "The company says its operations steer toward the unconventional. Unlike many other firms, all campaigns and creative design are done on the property. No contract agencies are involved in business operations. There are also no grand facilities to wear-test products, except for a turf area to test some aspects of shoe performance. The company says it prefers to use real-world conditions, including terrain differentiation and weather factors, while receiving feedback from various running clubs and their stable of athletes."

Although I have found no formal designation of centralized or decentralized structure I would lean towards decentralized. Several places I have read that the corporate culture is that of an athletic team. That team meetings are referred to as huddles and employees are treated as teammates instead of subordinates. These types of descriptions seem to create an environment where input is encouraged from all levels.