NEW YORK -- Forty years ago, the Mets stole Keith Hernandez from the Cardinals in a trade that sent right-handers Neil Allen and Rick Ownbey to St. Louis. The deal was a game changer for New York.

Hernandez was the driving force behind the Mets’ success from 1984-89. The team had five seasons of 90 wins or better, won two division titles (1986 and ‘88) and one World Series title, which occurred in 1986. Not only did Hernandez swing the bat with the best of them (.297 batting average in six-plus seasons), but he could pick it at first base. There was no one better defensively at that position than Hernandez during the 1980s.

“You didn’t realize sometimes how good a player he was until you watched him play every day,” Mets teammate Ron Darling said. “He just did something every day to not only help your team win, but something spectacular defensively or offensively that just separated him from anyone else that was in a Mets uniform.”

The Mets, who were 22-36 when the deal was made, had been at or near the bottom of the National League East the previous six years. But New York thought it had improved its club from the previous season.

The Mets had Tom Seaver, Rusty Staub and Mike Torrez, but they were past their prime. Dave Kingman and George Foster were supposed to supply thump in the batting order that year, but they had issues making contact. Even prized rookie, Darryl Strawberry, was off to a slow start.

A day before the June 15 Major League Trade Deadline, scouting director Joe McIlvaine and Mets general manager Frank Cashen were discussing how they could improve the team when the phone rang in Cashen’s office. It was Cardinals manager Whitey Herzog on the other line.

“He said, ‘I will give you Keith Hernandez for Neil Allen and either Rick Ownbey or Jeff Bittiger,’” McIlvaine remembered.

Cashen knew he was going to make the trade before he hung up the phone. They simply had to figure out which pitcher would go in the deal. The Mets decided that the 25-year-old Ownbey would go to St. Louis. The team felt Bittiger, then 21, had a brighter future in baseball.

Cashen called Herzog the next afternoon and made the deal.

“When Keith got traded, it was pretty much a shock,” said former Cardinals second baseman Ken Oberkfell, who played with Hernandez in the early 1980s.

The trade gave the Mets instant credibility with their fans. When it was announced on the Shea Stadium scoreboard that afternoon, “it was like a bomb had dropped,” McIlvaine remembered. “At first, there was silence in the ballpark with people walking in. All of a sudden, the fans started to clap, cheer and yell. They thought, ‘Wow, this is really interesting.’ I have never seen this before.”

According to a baseball source familiar with the trade talks, there was a feeling that Herzog didn’t want to make the trade. “It was ownership that forced this baby on him,” the source said.

Hernandez didn’t want to be traded either. He was dismayed after hearing the news. After all, the Mets hadn’t finished with a winning record since 1976.

“It was such an upheaval,” Hernandez said. “All I had known were the Cardinals. I grew up with them in the Minor Leagues. It was 8 ½ years in St. Louis. To get uprooted in the middle of the season, it’s just unsettling.”

Before the trade, Hernandez had been uneasy about roaming around New York City. It didn’t help that bench coach George Kissell gave Hernandez bad reviews about the Big Apple when Hernandez was a rookie in 1974.

“I came to New York in September and we flew in from St. Louis and got in late around 2 in the morning,” Hernandez recalled. “… [Kissell] tapped me on the shoulder and took me out.

“We were at New York Sheridan. He said, ‘Follow me.’ He took me out to the sidewalk. He pointed north toward Central Park and he said, ‘Don’t go there.’ Then he pointed south, ‘Don’t go down there.’ Then he pointed west and said, ‘Hell’s Kitchen, don’t go there.’ Then he kind of pointed a little northeast and said, ‘You can go to the Upper East Side if you want to go any place.’ I’m 20 years old and I have all the preconceived notions of New York being a dangerous place. … So I never really went out to New York when I was a Cardinal. I just went to the hotel bar. I ventured out one time.”

Hernandez had a chance to ask for a trade after the 1983 season, but instead opted to sign a five-year extension worth $8.4 million. What changed his mind?

The team had played better after his arrival, going 29-29 over the final two months, and teammate John Stearns insisted the Mets were about to turn the corner.

Then former Mets infielder Mike Phillips called Hernandez. The two had been Cardinals teammates from 1977-80. Phillips told Hernandez, “I was there when the team was terrible. New York is a great city. Really think hard about this. You could have a lot of fun.”

The final stamp of approval came from his father, John Hernandez. The older Hernandez convinced his youngest son that the Mets’ future was bright.

“During the strike year of ‘81, when ESPN was showing Minor League baseball, he saw Darryl down there,” Hernandez said. “He said, ‘They have a lot of young players down there. I think they have a lot of talent.’ I figured I made so many wrong decisions in my life, my dad always seemed to be right. My dad made the decision. I said I’m going to go with dad here with this one.

“Boy, I’m sure glad I changed my mind.”

The trade helped usher in an era of success for the Mets, and it was a life changer for Hernandez. His No. 17 was retired by the Mets last season, and he is now a longtime TV analyst for the Mets on SNY. He joined the network in 2006 and has won three local Emmy awards for best sports analyst.

“The trade expanded my life with what Manhattan and New York had to offer,” Hernandez said. “I have three daughters who were exposed to New York and the arts. So, everybody in my entire family was enhanced by the move to New York.”

As for Hernandez and Herzog, they later became friends.

“He said, ‘I did you the biggest favor trading you to New York,’" Hernandez recalled. “I go, ‘You know, you are right.’”