When Wetteland left the team following that season (in which they won the World Series), Rivera became the Yankees' closer and has remained so ever since. He has been perhaps the most consistent, dependable relief pitcher in the Major Leagues during his tenure as a closer for the Yankees. Rivera has been especially overpowering in the postseason, in which his lifetime earned run average, under 1 run per nine innings pitched, is among the best ever. His contribution to the general success of the Yankees since 1996, including four World Series championships, has been significant. However, in recent years his postseason performance has been a little less consistent, particularly in the 2001 World Series loss to the Arizona Diamondbacks and the infamous 2004 playoff collapse against the Boston Red Sox. His troubles with the Red Sox (although he continues to dominate against other teams) have continued, and during his introduction at the Red Sox opening day, he was lampooned with a standing ovation while his teammates were booed. To his credit, Rivera took the treatment with good humor and tipped his hat to the Red Sox fans.
Rivera has won the Rolaids Relief Man of the Year Award three times, in 1999, 2001, and 2004. He donated his 2001 trophy to the New York City Fire Department. It is on permanent display at the FDNY's Brooklyn headquarters. He won the World Series MVP Award in 1999, when which the Yankees swept the Atlanta Braves in four games and Rivera earned two saves.
Rivera's demeanor on the mound is very serious. His best pitches are his four-seam fastball and his cutter, which has been called the best pitch in baseball for a long time. On a per-batter basis, he probably breaks more bats than any other current pitcher, caused by jamming them with the fastball.
As Rivera enters a game in Yankee Stadium, the song "Enter Sandman" by Metallica is played on the loudspeaker system.
His uniform number is 42, which has been retired by all Major League Baseball teams since 1997 in honor of Jackie Robinson. However, Rivera is permitted to use the number due to a grandfather clause.