NEW YORK -- Aug. 28 will be a special day for former Major Leaguer Jerry Koosman when the Mets will retire his number, 36, at Citi Field.

Koosman, 78, will become the third player in Mets history to have his number retired. Tom Seaver (41) and Mike Piazza (31) are the others.

“It’s quite an honor, and I’m quite humbled by it,” Koosman said via telephone. “It’s humbling to think that the Mets thought that much of me.”

Koosman earned that honor. During his 12 years with New York from 1967-78, Koosman won 140 games, posted a 3.09 ERA and had one 20-win season. He helped the Mets upset the Orioles in the 1969 World Series and the Reds four years later in the National League Championship Series. If he had a better offense behind him, Koosman would have won more games. In 1977, he lost 20 games but with a respectable 3.49 ERA.

“I always thought when the going got tough, I wanted Jerry Koosman on the mound,” former Mets teammate Ed Kranepool said. “You look at all the important games we had, he was always one of the starting pitchers, whether it be the second game of the World Series or whether it would be a game against the Cubs [in 1969] where he knocked Ron Santo down. Koosman put an end to those knockdown pitches and he was the guy who would do it.”

Former teammate Ron Swoboda said while Seaver was the ace of the staff, Koosman was 1A. Koosman was at his best in the postseason.

In Game 2 of the 1969 World Series, Koosman was the stopper. He held the Orioles hitless until the bottom of the seventh inning, when Paul Blair led off with a single. The Mets held on, 2-1, to tie the series at one.

Three games later, the Mets were World Series champions, thanks to Koosman, who pitched a complete game at Shea Stadium. Catcher Jerry Grote, in an image cemented in Mets lore, leaped into Koosman’s arms after the final out.

“Coming behind Seaver, we don’t wear World Series rings if you don’t have a guy like Koosman,” Swoboda said. “Tom is the man and No. 1 in our rotation, but Koosman came behind him with the same kind of stuff.”

Koosman credits late manager Gil Hodges, whose No. 14 is retired, for the team upsetting Baltimore.

“He ran a great ship. He put together the players and the teamwork to get it done,” Koosman said. “So it was a lot of fun. … Everybody had the same set of rules. He was strict. He made us hold our heads high with hard work. That creates a strong team and unity.”

Koosman also relied on his own competitive fire to win games.

“The hitter is trying to beat you and you are trying to beat the hitter,” Koosman said. “So it comes down to who is going to do the best job, who tries the hardest, who has the best stuff that day.”

It’s amazing how Koosman’s professional career started. According to SABR’s Irv Goldfarb, Koosman played baseball for the U.S. Army in El Paso, Texas, and his batterymate was named John Luchese, who was impressed by what he saw from Koosman.

Luchese then wrote to his father, an usher at Shea Stadium, and told him about Koosman. The father passed word about Koosman to Joe McDonald, who worked in New York’s Minor League system. The Mets were impressed with what they saw and signed Koosman for $1,600 in August 1964, according to Goldfarb.

Koosman was in the big leagues for good starting in 1968. Koosman had a 19-year career that also included stints with the Twins, White Sox and Phillies. He finished his career with 222 wins and 2,256 strikeouts.

“He was a warrior,” Swoboda said. “You loved him because he was the kind of gamer that you wanted to hang out with. He played the whole game all the time and brought dominant stuff out there and a dominant attitude.”