Adjusted ERA+

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Adjusted ERA+, often simply abbreviated to ERA+ or ERA plus, is a statistic in baseball. It adjusts a pitcher's ERA according to the pitcher's ballpark (does it favor batters or pitchers) and the ERA of the pitcher's league. Average is set to be 100; a score above 100 indicates the pitcher performed better than average, below 100 indicates worse than average.

For instance, if the average ERA in the league is 4.00, and the pitcher is pitching in a ballpark that favors hitters, and his ERA is 3.80, then his ERA+ will be over 100. However, if the average ERA in the league is 3.00, and the pitcher is pitching in a ballpark favoring pitchers, and the pitcher's ERA is 3.20, then the pitcher's ERA+ will be below 100.

As a result, ERA+ can be used to compare pitchers across different run environments. In the above example, the first pitcher may have performed better than the second pitcher, but his ERA is higher. ERA+ can be used to correct this misleading impression.

Pedro Martínez holds the modern record for highest ERA+ in a single season; he posted a 1.74 ERA in the 2000 American League, which had an average ERA of 4.91, which gave Martinez an ERA+ of 285. While Bob Gibson has the lowest ERA in modern times (1.12 in the 1968 National League) the average ERA was 2.99 that year (the so-called Year of the Pitcher) and so Gibson's ERA+ is 258, still highly impressive, but only sixth since 1900. 1968 was the last year that Major League Baseball employed the use of a pitcher's mound greater than 10 inches.^[1]

The career record for ERA+ (with a minimum of 1,000 innings pitched) is held by closer Mariano Rivera, who has a career ERA+ of 199. The career record ERA+ amongst retired players is 148, held by Lefty Grove. Walter Johnson, Dan Quisenberry, Hoyt Wilhelm and Smokey Joe Wood are tied in second place with a career ERA+ of 146.

[edit] Leaders

Career Leaders Rank Player Adjusted ERA+ 1 Mariano Rivera 199 2 Pedro Martínez 154 3 Lefty Grove 148 4 Walter Johnson 146 Dan Quisenberry Hoyt Wilhelm Smoky Joe Wood 8 Ed Walsh 145 9 Johan Santana 144 10 Roger Clemens 143 Jim Devlin Brandon Webb 13 Addie Joss 142 Al Spalding 15 Roy Oswalt 141 16 Kid Nichols 139 17 Mordecai Brown 138 Cy Young 19 John Franco 137 Randy Johnson

Single Season Leaders Rank Player Adjusted ERA+ Year Team 1 Tim Keefe 294 1880 Troy Trojans 2 Pedro Martínez 291 2000 Boston Red Sox 3 Dutch Leonard 279 1914 Boston Red Sox 4 Greg Maddux 273 1994 Atlanta Braves 5 Walter Johnson 259 1913 Washington Senators Greg Maddux 1995 Atlanta Braves 7 Bob Gibson 258 1968 St. Louis Cardinals 8 Mordecai Brown 253 1906 Chicago Cubs 9 Pedro Martínez 245 1999 Boston Red Sox 10 Walter Johnson 240 1912 Washington Senators 11 Christy Mathewson 230 1905 New York Giants 12 Roger Clemens 226 1997 Toronto Blue Jays Dwight Gooden 1985 New York Mets 14 Grover Cleveland Alexander 225 1915 Philadelphia Phillies 15 Christy Mathewson 222 1909 New York Giants 16 Roger Clemens 221 2005 Houston Astros Pedro Martínez 1997 Montreal Expos 18 Lefty Grove 219 1931 Philadelphia Athletics 19 Jack Pfiester 216 1907 Chicago Cubs Cy Young 216 1901 Boston Americans

[edit] References