Arnoldo Hax, the Alfred P. Sloan Professor of Management Emeritus at the MIT Sloan School of Management and an operations management expert who introduced a customer-centered approach to competitive strategy with his Delta Model, died April 20. He was 87. Hax joined MIT Sloan in 1973 as a member of the Operations Management group. An industrial engineer who believed that management could be improved through rationalization, Hax was an early member of the strategy group at MIT Sloan, and strengthened ties with the School of Engineering. “He was a big…