MLB players are wearing number 21 to honor Roberto Clemente, a legendary baseball player and humanitarian. September 15th is celebrated as Roberto Clemente Day in Major League Baseball, marking the start of National Hispanic Heritage Month and paying tribute to Clemente's remarkable career and selfless acts off the field. All MLB players, managers, and coaches wear a "21" patch on their uniforms as a symbol of respect for Clemente, who wore number 21 throughout his career with the Pittsburgh Pirates. Additionally, players of Puerto Rican heritage, past winners, and nominees of the Roberto Clemente Award have the option to wear the number 21 on their jerseys. The award recognizes players for their philanthropic efforts in their communities, reflecting Clemente's deep passion for humanitarian work. This number and patches are also featured on bases and dugout lineup cards to celebrate his legacy.