Like at every noteworthy speakeasy, it started with a knock.
After Chad Thompson and his wife, Kitty, found the secret door in an unassuming section of Citi Field, home of the New York Mets, they faced one more test that day in June before securing access to perhaps Major League Baseball’s most exclusive new fan experience. They needed to recite the correct password. It had three words.
“Let’s go Mets,” Mr. Thompson, a resident of Manhattan, told the guard.
The couple walked into the Cadillac Club to catch a game between the Mets and their crosstown rival Yankees. Once inside, the Thompsons snacked on bacon-wrapped dates and complimentary glasses of prosecco and Glenfiddich 15-Year-Old Solera Reserve. They sat in plush brown leather seats with personal TVs attached, where they were served Shake Shack burgers and Häagen-Dazs ice cream bars. Directly in front of them, through a metal fence, was the diamond’s right field. Starling Marte, the Mets outfielder, tossed a few balls over to the fans seated in the club.
“It definitely does give you that V.I.P. feel, but you are a little isolated from the normal ballpark,” said Mr. Thompson, who was given the tickets (membership cost: up to $25,000 each per season) through a friend. “They make up for it, by just giving you…
