The facts
Koosman died on 1 November at age 83, MLB.com and CBS Sports reported, citing the Mets' announcement. [1][2]
He won 140 games for the Mets during 12 seasons with the club from 1967 to 1978. [1]
Koosman pitched a complete game in the Mets' Game 5 win over Baltimore that clinched the 1969 World Series. [1][2]
The Mets retired his No. 36 in 2021; MLB.com says his 140 wins remain a franchise high among left-handed pitchers. [1][2]
Still unconfirmed
- The reviewed reports did not identify a specific cause of death; CBS Sports said he had battled multiple illnesses.
Sources
References support the numbered facts above. Source checks: 1 Nov 2026, 20:45 UTC.
No family or club statement was retrieved. The death is attributed to MLB and CBS Sports, while career milestones are cross-checked against league records.
- Koosman, iconic Mets southpaw who clinched '69 WS, passes away at 83
Major League Baseball · Reporting · 1 Nov 2026
Opened MLB.com report of the Mets announcement, career record and World Series contribution.
- Mets legend Jerry Koosman dies at 83: Pitcher helped New York win 1969 World Series
CBS Sports · Reporting · 1 Nov 2026
Opened independently owned report corroborating death, 1969 title-clinching game and retired number.