The New York Mets are wearing number 21 to honor Roberto Clemente on Roberto Clemente Day, which is celebrated on September 15 each year. This day commemorates the life and legacy of Clemente, a Puerto Rican Hall of Famer who wore number 21 throughout his career. Major League Baseball recognizes the day by having all players, managers, coaches, and umpires wear a “21” patch on their uniforms, and players of Puerto Rican heritage, past Clemente Award recipients, and current nominees are allowed to wear number 21. The Mets, along with other teams, participate in this tribute usually by wearing the number 21 for the day or during specific games around that date.

Roberto Clemente was a legendary player and humanitarian who tragically died in 1972 during a relief mission to Nicaragua. MLB honors him not only by retiring his number 21 with the Pirates but also through this annual tribute day to celebrate his impact on baseball and the community.