López suffered from shoulder problems during spring training in 1982, and he was demoted to Detroit's Class AAA minor-league affiliate in Evansville by July. He was called back up to Detroit on September 1, but later that month he shocked his teammates by announcing that he was giving up his MLB career and returning to Mexico. López said that his reasons were personal, and he cited his family, the education of his children and the Mexican economy as motivating factors for the decision. He came out of retirement and returned to Detroit in time for the 1983 season. In February 1983, López became the first player in MLB history to receive a pay cut through salary arbitration. López had earned $285,000 in 1982, asked for $315,000 for 1983 and was awarded $250,000. He finished 1983 with a 9–8 record, 2.81 ERA and 18 saves.