With their homegrown core in place, the Mets put their roster over the top with the additions of Hernandez and Gary Carter, whom they acquired a year later in an offseason trade. Fans quickly came to love Hernandez for his slick glove and consistent hitting, both of which played significant roles in the team's 1986 World Series championship run.
In exchange, the Cardinals received three mediocre seasons from Allen, mostly as a reliever, and parts of two campaigns from Ownbey, who was out of baseball three years later.
No. 2: May 22, 1998 -- Mets receive Mike Piazza from the Marlins for Preston Wilson, Ed Yarnall and Geoff Goetz.
Eight days after the Dodgers traded Piazza to the Marlins in a blockbuster deal, the Fish flipped him north for a package of Wilson and two promising left-handed arms. They came to regret it. Yarnall and Goetz combined to pitch 20 innings in the big leagues, while Wilson made one All-Star team in 10 seasons.
Piazza, meanwhile, gave the Mets eight years of Hall of Fame-caliber production, leading them to the 2000 National League pennant and scoring six All-Star nods. He stands today as one of the greatest Mets hitters of all-time.
No. 3.: June 15, 1969 -- Mets receive Donn Clendenon from the Expos for Jay Carden, David Colon, Kevin Collins and Steve Renko.
The Mets were in second place in the NL East, nine games back from the Cubs, when they acquired Clendenon to provide some offensive pop. He delivered, hitting 12 home runs in 72 games to propel the Mets into the playoffs. That is where Clendenon did his best work, batting .357 with three home runs in four Fall Classic games to win World Series MVP Award honors.
Though Clendenon spent only parts of three seasons with the Mets, his impact in that brief time was substantial. Carden and Colon never made the big leagues, Collins batted .209 over a six-year career and Renko finished with a losing record in 15 seasons.
No. 4.: Aug. 28, 1984 -- Mets receive Ray Knight from Astros for players to be named later (Gerald Young, Manuel Lee and Mitch Cook).
Though Knight struggled in his first year and a half with the Mets, he transformed into a different player in 1986 -- just in time to play a key role in New York's World Series championship run. Mets fans will always remember Knight as the player who scored the winning run in Game 6 of the '86 World Series, when Mookie Wilson's grounder rolled through Bill Buckner's legs.
Young played eight years in the big leagues, finishing with a .269 career average. Lee hit .255 with 19 homers in his 11-year career, while Cook never made the Majors.
No. 5.: July 28, 2011 -- Mets receive Zack Wheeler from the Giants for Carlos Beltran and cash.
The jury is certainly still out on Wheeler, who has made a total of five Major League starts for the Mets. But the Mets quite simply can't lose this trade, considering what they gave up.
Beltran was 34 years old at the time of the trade, enjoying a strong first half but struggling to stay healthy. The non-contending Mets had no interest in re-signing him after the season, and a clause in Beltran's contract stipulated that the Mets could not offer him arbitration, meaning they could not receive a compensatory Draft pick had he signed elsewhere.
So although the entire league knew the Mets would trade Beltran, sabotaging general manager Sandy Alderson's leverage, the GM still managed to extract Wheeler. The right-hander has since developed into one of the top pitching prospects in franchise history, while the Giants missed the playoffs and were unable to re-sign Beltran after that season.