Jerry Koosman Dies at 83 After 19 MLB Seasons

Former Major League Baseball pitcher Jerry Koosman has died at 83, the New York Mets announced on November 1, 2026. A 19-season veteran, Koosman became one of the most important players in franchise history through his contributions to the team's first World Series championship in 1969.

Koosman spent his first 12 major league seasons with New York, earning two All-Star selections and establishing a lasting partnership with fellow pitcher Tom Seaver. The Mets honored his contributions by retiring his No. 36 jersey and inducting him into their Hall of Fame, according to MLB Trade Rumors.

His professional baseball opportunity emerged while he was serving in the Army in the United States. A fellow serviceman, John Luchese, learned about Koosman's pitching ability and passed the information to his father, who worked as an usher at Shea Stadium. The Mets subsequently scouted Koosman and signed him in 1964.

Koosman made his major league debut in 1967, appearing in nine games and recording 22 1/3 innings. He delivered a breakthrough performance the following season, posting a 2.08 ERA across 263 2/3 innings in 35 games.

That performance earned him his first All-Star selection and a second-place finish in National League Rookie of the Year voting. Seaver had won the award the previous year, and the two pitchers became the foundation of New York's starting rotation.

Their emergence helped transform a franchise that had endured seven consecutive losing seasons. During the 1969 championship campaign, Koosman recorded a 2.28 ERA across 241 regular-season innings, according to MLB Trade Rumors.

He also delivered in the World Series, producing a 2.04 ERA over 17 2/3 innings. Koosman won both of his starts against the Baltimore Orioles, including a complete-game performance in Game 5 that secured the championship for New York.

His subsequent achievements included another National League pennant in 1973 and a second-place finish in National League Cy Young Award voting in 1976. Across 2,544 2/3 innings with the Mets, he recorded a 3.09 ERA.

Those figures placed him sixth in franchise history for innings pitched and second in ERA among the club's historical leaders, according to MLB Trade Rumors. His 346 starts ranked second behind Seaver in the team's record books.

Koosman's departure from New York followed difficult seasons for the franchise. After Seaver was traded to the Cincinnati Reds in 1977, another disappointing campaign in 1978 prompted Koosman to request a trade. The Mets subsequently sent him to the Minnesota Twins that winter.

His first season in Minnesota became the most productive of his career by FanGraphs' fWAR measure, reaching 5.5. He posted a 3.38 ERA over 263 2/3 innings and finished sixth in American League Cy Young Award voting.

Koosman spent his final seven seasons with the Twins, Chicago White Sox and Philadelphia Phillies. Knee problems restricted him to 99 1/3 innings in 1985, prompting his retirement at the end of that season.

He finished his major league career with 222 wins, 2,556 strikeouts and a 3.36 ERA across 3,839 1/3 innings. His career walk rate was 7.5%, according to MLB Trade Rumors.