Prior to the start of the 1987 season, Reardon was again traded—this time to the Minnesota Twins along with catcher Tom Nieto—for pitchers Neal Heaton, Yorkis Pérez, and Alfredo Cardwood and catcher Jeff Reed. Although his performance dropped as compared to his previous five seasons, the trade would immediately pay dividends for the team as he would help the Twins win the 1987 World Series. The next season, he reverted to form, was named to his third All-Star team, and became the first pitcher in Major League Baseball history to have 40-save seasons in both the American and National Leagues. After another good season in 1989, Reardon became a free agent and signed with the Boston Red Sox on December 6. In honor of Reardon's signing, his birthplace of Dalton, Massachusetts, named its athletic field after him. After saving "only" 21 games for the Red Sox in 1990, Reardon was named to his fourth and final All-Star team in 1991 after another 40-save season. He broke Rollie Fingers' all-time saves record in 1992 with his 342nd save. Later that season, he was traded to the Atlanta Braves for starting pitcher Nate Minchey and minor league outfielder Sean Ross. With the Braves, he pitched in his second World Series and was responsible for two of Atlanta's four losses versus Toronto, blowing a save in Game 2 and giving up the winning hit in Game 3.