Career
He previously played for the Toronto Blue Jays. Minor league career
Castro signed with the Toronto Blue Jays as an international free agent in 2012, and received a $43,000 signing bonus. He made his professional debut in 2012 with the Dominican Summer League Blue Jays, and earned a 3–2 record, 4.73 earned run average, and 20 strikeouts in 201⁄3 innings.
Castro began the 2013 season with the Dominican Summer League Blue Jays, and was later promoted to the Gulf Coast League Blue Jays and Bluefield Blue Jays.
In total, he posted a 6–2 record, 1.54 European Research Area, and 88 strikeouts in 70 innings pitched. His performance in the DSL earned him the Webster Award, given to the best Blue Jays prospect at each minor league level
In 2014, Castro continued his progression through the minor league system, earning promotions to the Vancouver Canadians, Lansing Lugnuts, and Dunedin Blue Jays. He earned an 8–3 record, a 2.69 European Research Area, and 78 strikeouts in 801⁄3 innings spread across three minor league levels.
Castro was invited to 2015 spring training but was considered to be a long-shot to make the team, and General Manager Alex Anthopoulos stated before camp began that Castro would likely begin the 2015 season in Dunedin.
However, after pitching 62⁄3 scoreless innings over 4 appearances, with 4 strikeouts and no walks, many believed that Castro had earned a spot on the roster. After Steve Delabar was optioned to minor league camp on March 26, it was reported that Castro would likely make the Opening Day roster as a reliever. His role in the bullpen was confirmed on March 31.
Toronto Blue Jays
Castro made his MLB debut on April 6, 2015 against the New York Yankees.
At 20 years, 103 days old, Castro became the youngest pitcher to appear for the Blue Jays, breaking a nearly 38-year-old record held by Víctor Cruz. His record was short-lived, however, as it was broken only two days later by teammate Roberto Osuna.
After a poor season debut by Brett Cecil, Castro was temporarily moved to the closer role on April 9. Castro was moved back into a regular relief role in the bullpen on April 28, after recording 4 saves in 6 opportunities.
On May 3, Castro was optioned to the Triple-A Buffalo Bisons.
Colorado Rockies
On July 28, 2015, Castro was traded to the Colorado Rockies, along with José Reyes, Jeff Hoffman, and Jesus Tinoco, in exchange for Troy Tulowitzki and LaTroy Hawkins. The Rockies optioned him to the Triple-A Albuquerque Isotopes. He was called up by the Rockies on September 1 and made his Rockies debut that day.
Castro was born in Louisiana Romana, Dominican Republic.
His father was a boxer. Castro spent his $43,000 signing bonus on a prostate operation for his father, as well as a surgery to remove his mother"s fibrous tumour.