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Baseball Judgments

Baseball Judgments | SportsLibrary.net
Era adjustments

 

By Roger Weber

 

For years statisticians have tampered with adjustments for differences in the game due to different overall levels of play. In many respects I have all but abandoned them in many of my studies, because they fluctuate greatly depending on the formula used to get them. And conceptual problems with discrediting records or players because they happened to play perhaps in a time without modern technology and workout regimens seem unfair.

 

Still, there is some value to knowing how the quality of play was different between eras. One way of measuring this is to measure the run disparities between the best team in the league and the worst team in the league. When that difference is small, it could be said that the competition is tighter, and thus more talented. As we can see, that difference has decreased over the years in the National League (as shown in the graph below), meaning that according to this method competition is better now.

 

Click here to download graph

 

But with baseball, where today there are hundreds if not thousands of players capable of performing just fine in the major leagues, that methodology seems a little flawed. So estimations are also made based on changes to the makeup of the majors – the inclusion of blacks, changes to the ball, steroids, etc.

 

Given that they are certainly imperfect, here are a set of usable era adjustments. 1 is a completely arbitrary average. And numbers above 1 measure how much better than 1 the era was. For example, if an era's rating is 1.05, it was 5% better than average and statistics from that era should be inflated 5% against the same statistics from an era with a score of 1.

 

Time

NL

AL

2005

1.11

1.13

2000

1.12

1.14

1995

1.08

1.11

1990

1.04

1.07

1985

1.03

1.07

1980

1.05

1.09

1975

1.05

1.05

1970

1.04

1.02

1965

1.02

1.01

1960

1.03

1.03

1955

1.04

1.05

1950

1.05

1.06

1945

1.02

1.02

1940

1.01

1.03

1935

1

1.01

1930

1

1

1925

.97

.98

1920

.97

.97

1915

.96

.96

1910

.95

.95

1905

.94

.95

1900

.97

.97

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