Mr. Hernandez landed in New York in the 1970s with the St. Louis Cardinals, a West Coast kid in Sodom and Gomorrah. A Cardinals coach took him to Seventh Avenue and pointed north to Central Park. “Don’t go there.” He pointed south to Times Square. “Don’t go there.” He pointed west to Hell’s Kitchen. “Don’t go there.”

He pointed to the Upper East Side. “You can go there. By taxi.”

Mr. Hernandez remained at the hotel bar. The international airlines booked the same hotel as the ballplayers. “It was always Air France, and their stewardesses would come down to the bar for pops.” He shrugged. “You could call that my education.”

He married early, had three girls and got divorced. When he was traded to the Mets in 1983, he moved to Manhattan and discovered a world of possibility. He remarried last decade and moved to Sag Harbor. “That marriage is kaput,” Mr. Hernandez says.

He has picked up the pieces. He has a beloved Bengal tiger cat. And he is dating, leave it at that.

In the living room, he shows you his books — he loves Victor Hugo, Jack London and Joseph Conrad, and he will embark on “Moby-Dick” in the off-season. He has $30,000 Italian speakers. He began as a “ ’60s rocker,” he said: Jimi, Cream, the Stones, Led Zeppelin. His tastes have expanded to Sinatra, Ella, Miles and Willie Nelson.

Bobby Zarem, the ubiquitous publicist, took him to the opera. They knocked on Plácido Domingo’s backstage door. The tenor sat on a throne and threw up his arms: “Keith! I have a cold. I sang like a .230 hitter tonight. Next time I’ll be a .300 hitter.”

Former President Richard Nixon once visited the Mets locker room. The photograph is on a bureau: the former president in a suit and tie and Keith naked from the waist up. They shared lunches. Nixon wanted to talk about the stars of the ’86 team — Lenny Dykstra, Mookie Wilson, Dwight Gooden. One day Mr. Hernandez blurted out: “Mr. President, all we do is talk baseball. Could we talk politics?”