Earned run average
In
Origins
After pitchers like
Baseball encyclopedias will often display ERAs for earlier years, but these were computed retroactively. Negro league pitchers are often rated by RA, or total runs allowed, since the statistics available for Negro league games did not always distinguish between earned and unearned runs.
ERA in different decades
As with batting average, the definition of a good ERA varies from year to year. During the dead-ball era of the 1900s and 1910s, an ERA below 2.00 (two earned runs allowed per nine innings) was considered good.[1] In the late 1920s and through the 1930s, when conditions of the game changed in a way that strongly favored hitters, a good ERA was below 4.00; only the highest caliber pitchers, for example Dazzy Vance or Lefty Grove, would consistently post an ERA under 3.00 during these years. In the 1960s, sub-2.00 ERAs returned as other influences, such as ballparks with different dimensions, were introduced. Starting with the 2019 season, an ERA under 4.00 is again considered good.
The single-season record for the lowest ERA is held by Dutch Leonard, who in 1914 had an earned run average of 0.96, pitching 224.2 innings with a win–loss record of 19–5.[2] The all-time record for the lowest single season earned run average by a pitcher pitching 300 or more innings is 1.12, set by Bob Gibson in 1968. The record for the lowest career earned run average is 1.82, held by Ed Walsh, who played from 1904 through 1917.
Infinite and undefined
Some players may be listed with infinite ERAs. This can happen if a pitcher allows one or more earned runs without retiring a batter. Several players have registered an infinite ERA for their limited pitching careers in MLB, usually a single appearance. Examples include
An undefined ERA occasionally occurs at the beginning of a baseball season when a pitcher has yet to appear in any games. It is sometimes incorrectly displayed as zero or as the lowest-ranking ERA.
Other external factors
Starters and relievers
At times it can be misleading to judge relief pitchers solely on ERA, because they are charged only for runs scored by batters who reached base while batting against them. Thus, if a relief pitcher enters the game with his team leading by 1 run, with 2 outs and the bases loaded, and then gives up a single which scores 2 runs, he is not charged with those runs. If he retires the next batter (and pitches no more innings), his ERA for that game will be 0.00 despite having surrendered the lead. (He is recorded with a
ERA, taken by itself, can also be misleading when trying to objectively judge starting pitchers, though not to the extent seen with relief pitchers.
Designated hitter rule
The advent of the designated hitter rule in the American League in 1973 made the pitching environment significantly different. From then up through 2021, pitchers spending all or most of their careers in the AL, while not usually having to worry about batting themselves, had been at a disadvantage in maintaining low ERAs compared to National League pitchers who could often get an easy out when pitching to the opposition's pitcher. Starting in 1997, when teams began playing teams from the other league during the regular season, the DH rule was in effect only when such interleague games are played in an American League park; this was rendered moot after the National League permanently adopted the DH in 2022.
This difference between the leagues (the DH) also affected relievers, but not to the same degree. This is because National League relievers actually pitched to pitchers less often than NL starters did for a number of reasons, chiefly because relievers are usually active in later innings when the double switch was available and/or pinch hitters tended to be used in the pitcher's batting spot.
Location
ERA is also affected somewhat by the ballpark in which a pitcher's team plays half its games, as well as the tendency of hometown official scorers to assign errors instead of base hits in plays that could be either.
As an extreme example, pitchers for the Colorado Rockies have historically faced many problems, all damaging to their ERAs. The combination of high altitude (5,280 ft or 1,610 m) and a semi-arid climate in Denver causes fly balls to travel up to 10% farther than at sea level. Denver's altitude and low humidity also reduce the ability of pitchers to throw effective breaking balls, due to both reduced air resistance and difficulty in gripping very dry baseballs. These conditions have been countered to some extent since 2002 by the team's use of humidors to store baseballs before games. These difficult circumstances for Rockies pitchers may not adversely affect their win–loss records, since opposing pitchers must deal with the same problems. Indeed, hometown hurlers have some advantage in any given game since they are physically acclimated to the altitude and often develop techniques to mitigate the challenges of this ballpark. Still, conditions there tend to inflate Rockies' ERAs relative to the rest of the league.
Sabermetric treatment of ERA
In modern baseball,
In
All-time career leaders
Rank | ERA | Player | Team(s) | Year(s) |
---|---|---|---|---|
1 | 1.82 | Ed Walsh | Boston (NL)
|
1904–17 |
2 | 1.89 | Addie Joss | Cleveland (AL)
|
1902–10 |
3 | 1.89 | Jim Devlin | Chicago (NA), Louisville (NL) | 1875–77 |
4 | 2.02 | Jack Pfiester | Pittsburgh (NL), Chicago (NL) | 1903–04, 1906–11 |
5 | 2.03 | Smoky Joe Wood | Cleveland (AL)
|
1908–15, 1917–22 |
Career leaders in the live-ball era (post-1920, Starting Pitchers Only)
Because of rules changes post-1920, most notably the abolition of the spitball and frequent replacement of soiled or scuffed baseballs, the increased importance of the home run (largely due to
This is a list of the lowest ERAs among pitchers that played their entire careers after 1920 (minimum 1,500 innings pitched, starting pitcher).
Rank | ERA | Player | Team(s) | Year(s) |
---|---|---|---|---|
1 | 2.48 | Clayton Kershaw | Los Angeles (NL) | 2008– |
2 | 2.75 | Whitey Ford | New York (AL) | 1950–67 |
3 | 2.76 | Sandy Koufax | Brooklyn/Los Angeles (NL) | 1955–66 |
4 | 2.86 | Jim Palmer | Baltimore (AL) | 1950–67 |
5 | 2.86 | Andy Messersmith | 1968–79 | |
6 | 2.86 | Tom Seaver | New York, Cincinnati, New York, Chicago, Boston, Chicago, Boston | 1967–86 |
See also
References
- ^ "MLB rule changes in 2023".
- ^ according to www.mlb.com, the official website of Major League Baseball
- ^ Schwarz, Alan (August 22, 2004). "Numbers Suggest Mets Are Gambling on Zambrano". The New York Times. Retrieved July 19, 2011.
- ^ Silver, Nate (September 27, 2006). "Lies, Damned Lies: Playoff Hurlers". Baseball Prospectus. Prospectus Entertainment Ventures. Retrieved July 19, 2011.