The team had planned to have his number retired during the 2020 season, but due to COVID-19 they postponed the event.
Koosman will join Tom Seaver (No. 41) and Mike Piazza (No. 31) as the only Mets players to have their number retired. The Mets have also retired manager Casey Stengel‘s No.37, manager Gil Hodges‘ No. 14, and Jackie Robinson‘s No. 42 — as MLB did in unison in 1997.
The lefty helped lead the Mets to their first World Series title in 1969, as he went 17-9 with a 2.28 ERA and 180 strikeouts.
“The excitement of playing for the Mets when we won the 1969 World Series was an experience I never thought I’d be able to repeat,” Koosman said in a press release. “But the news that the Mets Hall of Fame Committee has voted to retire my number is another life-changing thrill and honor.”
He finished his career with a 222-209 record and a 3.36 ERA with 2,556 strikeouts over 19 seasons in the MLB, including 12 years with the Mets from 1967-1978. Koosman earned two All-Star appearances over his career (1968, 1969) and retired after the 1985 season.
“This honor isn’t only for me and my family, it’s for the legions of fans I grew to love,” Koosman continued. “To know that my number will be retired and sit alongside other team legends is one of the greatest tributes I could ever be granted. I was always proud to be a Met. Today, I am even prouder.”