NEW YORK (AP) — Jerry Koosman will become the third New York Mets player to have his number retired by the team.

The left-hander will be honored sometime next season, with his No. 36 joining Tom Seaver's No. 41 and Mike Piazza's No. 31 on display along the Citi Field roof. Chief operating officer Jeff Wilpon announced the plans Tuesday on the 50th anniversary of New York winning its first championship, the 1969 NL East title, with a pitching staff led by Seaver and Koosman.

"This honor isn't only for me and my family, it's for the legions of fans I grew to love," Koosman said in a statement. "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."

Wilpon surprised Koosman with the news during a recent phone call.

"He was so excited, I don't think he really understood what was happening," Wilpon said. "To hear the excitement in his voice as it sunk in and he understood what the magnitude of this honor was, it was really great to be part of that. ... He was honored to be the next guy."

The Mets have also retired the numbers of ex-managers Casey Stengel (No. 37) and Gil Hodges (No. 14). Jackie Robinson's No. 42 was retired by all major league clubs in 1997.

Koosman will be the first player not elected to the Baseball Hall of Fame in Cooperstown to have his uniform number retired by the Mets.

"I think we see the fans want it and I think now that we're 50 years-plus in the making, that there's time to do it," Wilpon said. "There's a plan going forward for Hall of Fame and number retirement that we're going to spread 'em out, not to overload anything. But I think we have a plan to catch up and do some neat things for the fans."

Current manager Mickey Callaway has been wearing No. 36 but said he was glad to switch. He changed to No. 26 for Tuesday night's game against Miami.

"I jumped on that," Callaway explained. "This guy's legacy needs to be cemented on the side of the stadium here."

Koosman pitched for the Mets from 1967-78 and won twice during the 1969 World Series, throwing a complete game to beat heavily favored Baltimore 5-3 in the clincher. He was at Citi Field in late June for anniversary ceremonies saluting those Miracle Mets.

"I think it bookends our celebration of the '69 season pretty well," Wilpon said.

The 76-year-old Koosman ranks third in franchise history with 140 wins, most among left-handers. He is second in starts (346), complete games (108), innings (2,544 2/3) and shutouts (26), third in strikeouts (1,799), and sixth in ERA (3.09). He went 4-0 in the postseason with the Mets.

The two-time All-Star was a close runner-up to Hall of Fame catcher Johnny Bench for NL Rookie of the Year in 1968, when Koosman won 19 games with a 2.08 ERA and seven shutouts. He finished second to San Diego's Randy Jones in 1976 Cy Young Award voting.

"Jerry is one of the most iconic Mets of all-time and this forever honor is a tremendous representation of what he meant to the organization," Wilpon said in the statement.

Koosman was scouted by the Mets while he was pitching with the U.S. Army. He was inducted into the club's Hall of Fame in 1989.

The date of next year's ceremony for Koosman will be announced in the coming weeks, the Mets said.

"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. "But the news that the Mets Hall of Fame Committee has voted to retire my number is another life-changing thrill and honor."

More From 1460 ESPN