Jerry Koosman, the left-handed pitcher who closed out a 19-year major league career with the Philadelphia Phillies, died Sunday at his home in Osceola, Wisconsin.

He was 83.

Koosman passed away from heart failure after roughly a year of various ailments, according to longtime Mets spokesperson Jay Horwitz.

He was surrounded by family.

While Koosman is best remembered as a cornerstone of the 1969 “Miracle Mets” World Series champions—pairing with Tom Seaver and throwing a complete game to clinch the title in Game 5—his final two seasons came in Philadelphia.

The Phillies acquired him from the Chicago White Sox in February 1984, completing a deal that had sent reliever Ron Reed to Chicago the previous December.

At age 41 in 1984, Koosman proved a reliable innings-eater, going 14-15 with a 3.25 ERA over 224 innings and 34 starts.

He struck out 137 while allowing just eight home runs.

One moment that still resonates for Phillies fans occurred on April 13 of that year, when Koosman surrendered a double to Pete Rose for Rose’s 4,000th career hit.

He returned in 1985 at 42, posting a 6-4 record with a 4.62 ERA in 19 appearances (18 starts) and 99⅓ innings before the Phillies released him after the season.

His final major league appearance came August 21 against the Dodgers. Across his two years in red pinstripes, Koosman went 20-19 with a 3.67 ERA in 323⅓ innings.

For Phillies supporters, Koosman represented the end of an era—a veteran lefty who still had enough left to log meaningful work late in his career, even if he arrived long after his peak.

Career-wide he finished 222-209 with a 3.36 ERA, 2,556 strikeouts, and 140 complete games, ranking among the more durable pitchers of his generation.

The Mets inducted him into their Hall of Fame in 1989 and retired his No. 36 in 2021. He is survived by a daughter, Danielle; sons Shawn and Michael; and several grandchildren.