Right handed pitcher Juan Castillo was signed as a free agent by the Mets in 1988. After spending six seasons in the minors he finally got the call to join the Mets on July 26, 1994 against the St Louis Cardinals. Castillo started the game but allowed five runs over five innings in a game the Mets would win 10-9. He started one more game five days later against the Pittsburgh Pirates with similar results. He pitched 6 2/3 innings and allowed four runs, once again the Mets would win the game 6-4. During the game Castillo did manage to get his first major league hit, an RBI single in the 4th inning. Following the game Castillo was shipped back to the minors where he finished out the season with the Norfolk Tides.
The Mets traded Juan Castillo to the Houston Astros in the off-season; he spent three seasons in their minor league system before spending one season with the Texas Rangers organization. He retired following the 1996 season.
In two games for the Mets Juan Castillo posted a 6.94 ERA in 11 2/3 innings.
While with the Mets Castillo wore number 50.