Although Indians manager, Lou Boudreau, named Gene Desautels as the Indians starting catcher at the beginning of the 1943 season, by the middle of the year Rosar was among the league leaders in hitting with a .313 average. He was recognised by being named to his second All-Star team as a reserve in the 1943 All-Star Game. He ended the season with a .283 batting average and 41 runs batted in. He also led American League catchers in assists and in baserunners caught stealing. In 1944, Rosar was assigned to a war job in Buffalo, New York before being transferred to another war job in Cleveland, leaving him available part-time to the Indians. He was again hitting among the league leaders with a .324 average in June before fading to finish the year with a .263 batting average. After two seasons with the Indians, Rosar refused to play at the beginning of the 1945 season because of a salary dispute. The Indians responded by trading Rosar to the Philadelphia Athletics for catcher Frankie Hayes on May 29, 1945.