[2] At the age of 15, Candelaria attended a baseball tryout where a Los Angeles Dodgers scout called him the best[clarification needed] he had ever seen.

Candelaria played as a center in the Baloncesto Superior Nacional (BSN), the top tier basketball league in the Puerto Rico, for 2 seasons with the Piratas de Quebradillas in 1971 and 1972.

He had attended La Salle Academy in lower Manhattan and gained fame as a basketball center, including leading his team to a championship in 1971.

He struck out 14 Reds and pitched eight innings, but gave up a game-tying two-run home run to Pete Rose in the eighth.

Candelaria, who stood 6 feet 7 inches (2.01 m) and wielded a mid- to upper-90s fastball with natural movement, remained an effective starter for the Pirates through the 1984 season.

He suffered personal tragedy on Christmas morning 1984, when his 18-month-old son John Jr. fell into the family's swimming pool at their home in Sarasota, Florida.

In response to the change, Candelaria called general manager Harding Peterson "a bozo"; he said that the team's ownership valued its racehorses more than its baseball players.

[6] Candelaria and George Hendrick once confronted their Angels teammate Reggie Jackson about his bullying of Lisa Nehus Saxon.

[9] In 1989, Yankee manager Dallas Green looked to give Candelaria some extra rest at the start of the year, as the pitcher was recovering from a knee injury.