The historical value has
always been considered to be near 10 runs per win, with a historical value of
8.85. The higher the value, the greater the level
of offense, and the lower, the more that pitching is dominant. This works well
when viewing data in terms in these terms (all years approximate):
1901-1919 The Dead Ball Era
1920-1945 The Lively Ball Era (the dip at the end is due to World War II)
1920-1945 The Lively Ball Era (the dip at the end is due to World War II)
1946-1960 The No Label Era
1961-1993 The Expansion Era
(with a Mini Dead Ball Era from 1962-1968)
1994-2007 The “Enhanced
Offense” Era
2008- The “Back To Normal” Era
2012 crossed underneath that
112-year average line, and when that occurs, other facets of the game, like
base running and defense come to the front. With regard to defense, if we can
establish the number of runs equals a win, we can also see how many errors equal
a run in a similar fashion, which is simply unearned runs/errors. Before I show
that, this next chart shows the percent of runs that were unearned from
1901-2012:
This is one piece of evidence that defense DOES continue to improve, either through better technique, better positioning, or more likely a combination of that and other factors. Despite the rapid improvement from 1901-1920, from 1920 on the number of unearned runs has decreased by a factor of 2, which is tremendous. This next chart shows the ratio of unearned runs to errors:
Most of the fluctuation is due to the scale—in this 100+ time span, the value of an error lies between .55 and .65 runs, or in other words, every two errors will lead to a run. Of course, this isn’t game-specific, but it helps see what errors can cost a team.
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