January 13 — Major League Baseball announced on Monday that San Francisco Giants minor league pitcher Luis Custodio and free agent minor league pitcher Luis Sierra have each been suspended for 56 games following violations of the league’s drug policy.
According to MLB, both pitchers tested positive for Stanozolol, a banned performance-enhancing drug, in violation of Minor League Baseball rules. As a result, the suspensions will be served without pay under the Minor League Drug Prevention and Treatment Program.
Custodio, 21, is currently on the roster of the Dominican Summer League Giants Black. Because the Dominican Summer League is not active at this time, his suspension will begin at the start of the 2026 DSL season. Custodio remains under contract with the Giants organization and will be prohibited from participating in official games during the suspension period.
Sierra, 20, faces a different situation. As a free agent, he will not begin serving his suspension until he signs with a Major League Baseball organization. Sierra pitched during the 2025 season for the Dominican Summer League Orioles Orange, but is not currently affiliated with a team. Once he signs a minor league contract, the 56-game suspension will immediately go into effect.
Neither Custodio nor Sierra has appeared above the rookie level of the minor leagues. Both pitchers were still in the early stages of their professional development, making the suspensions a significant setback to their careers. Time away from competition could slow their progression and impact future opportunities within professional baseball.
Stanozolol, an anabolic steroid, has long been listed as a prohibited substance under MLB’s drug policies. The league conducts routine testing across all minor league levels, including international leagues such as the Dominican Summer League, as part of its broader effort to maintain competitive integrity and player safety.
MLB has continued to emphasize education and enforcement in its drug prevention program, particularly for young and international players. Despite those efforts, the league maintains a strict liability standard, meaning players are responsible for any banned substances found in their system regardless of intent.
The suspensions serve as another reminder that Major League Baseball applies its anti-doping rules uniformly across all levels of the sport. For Custodio and Sierra, the focus now shifts to serving their penalties and working toward a return to competition once eligible.