He was drafted by the Mets in the 1966 Major League Baseball draft and backed up Jerry Grote as a member of the 1969 Miracle Mets team that went on to win the World Series. Dyer caught most of the Mets games in 1972, as Grote battled injuries. In 94 games, he posted career-highs with 8 home runs and 36 runs batted in. He also led National League catchers in double plays and in baserunners caught stealing, finished second in assists and, third in fielding percentage. In 1973, Dyer was part of the Mets team that staged another miraculous season when they came from last place on August 30 to win the National League Eastern Division pennant.