Born in Los Angeles, he threw and batted right-handed, stood 5 feet 11 inches (1.80 m) tall and weighed 170 pounds (77 kg).

After attending the University of San Francisco,[1] Caulfield began his pro career during World War II at the relatively advanced age of 25 for the Oakland Oaks of the top-level Pacific Coast League, appearing in 152 games in 1943.

[3] In Charlie Metro's autobiography, this is what he wrote about the 1946 trade that brought Jake Caulfield from the Oakland Oaks to the Philadelphia Athletics: "The Athletics needed a shortstop, so they traded Charlie Gassaway, Ed Busch, and me to Oakland for Jake Caulfield, all the way across the continent in the Pacific Coast League.

Every time I'd see Jake Caulfield, who later retired from the San Francisco police force, at spring training at Phoenix, I'd tell him, 'I'm going to punch you right now.'

[4] Caulfield returned to the minor leagues for his final two professional seasons at the Triple-A level, playing for the Sacramento Solons and Columbus Red Birds in 1947 and for the Rochester Red Wings and San Diego Padres in 1948.