In 2019, Del Castillo's freshman season with the Miami Hurricanes, he started 61 games and hit .331/.418/.576 with 12 home runs and 72 runs batted in (RBIs).[4][5] He spent a majority of his time in right field but also spent time at catcher, third base, and designated hitter.[6] He was named to the All-Atlantic Coast Conference Freshman Team and Second Team alongside earning Freshman-All American honors from various outlets.[7][8] That summer, he played in the Cape Cod Baseball League for the Wareham Gatemen.[9][10][11] For his sophomore season in 2020, Del Castillo was expected to shift primarily to catching.[12] He hit .358 with two home runs and 15 RBIs over 16 starts before the college baseball season was cut short due to the COVID-19 pandemic.[13] For the 2021 season, Del Castillo appeared in 54 games in which he batted .275 with three home runs and 37 RBIs.[14]
Del Castillo was assigned to Reno to open the 2024 season.[21] In 100 games for Reno, he batted .319/.403/.608 with 24 home runs and 70 RBI. On August 6, 2024, Del Castillo was selected to the 40-man roster and promoted to the major leagues for the first time.[22] On August 9, against the Philadelphia Phillies, Del Castillo became the first Diamondbacks player in franchise history to have a walk-off home run as their first in the major leagues.[23] On August 18 against the Tampa Bay Rays, Del Castillo hit a three-run home run that tied the game in the ninth, but the Diamondbacks lost in extra innings.[24] The next day against the Miami Marlins, Del Castillo hit his first career grand slam and recorded 6 RBI in front of his friends and family in his hometown of Miami.[25] In 25 games during his rookie campaign, Del Castillo slashed .313/.368/.525 with four home runs and 19 RBI. After the season, he won the Pacific Coast League Most Valuable Player Award.[26]
