The Houston Astros players and coaches are wearing the number 21 today in honor of Roberto Clemente Day. This day commemorates the legacy of Roberto Clemente, a Baseball Hall of Famer who wore number 21 throughout his career. Clemente is celebrated not only for his outstanding baseball achievements but also for his humanitarian efforts and fight against racism and discrimination. The Astros, including several Puerto Rican players and others, are wearing the number 21 to pay tribute to Clemente's life and impact, particularly on September 15, 2025, which is recognized as Roberto Clemente Day in MLB.