Edward Augustine Walsh was an American pitcher and manager in Major League Baseball, nicknamed "Big Ed". From 1906 to 1912, he had several seasons where he was one of the best pitchers in baseball. Injuries shortened his career. Walsh holds the record for lowest career earned run average, 1.82. He is one of two modern (post-1901) pitchers to win 40 or more games in a single season, and the last pitcher to do so. He is the last pitcher from any team to throw more than 400 innings in a single season, a feat he accomplished in 1907 and 1908. He was inducted into the Baseball Hall of Fame in 1946.

In baseball statistics, earned run average (ERA) is the average of earned runs allowed by a pitcher per nine innings pitched. It is determined by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine. Thus, a lower ERA is better. Runs resulting from passed balls, defensive errors, and runners placed on base at the start of extra innings are recorded as unearned runs and omitted from ERA calculations.