What is Sabermetrics?

By Wikipedia

Sabermetrics is the analysis of baseball through objective evidence, especially baseball statistics. The term is derived from the acronym SABR, which stands for the Society for American Baseball Research. It was coined by author Bill James, who has been its most well-known proponent. It should be noted that many at SABR view sabermetrics with skepticism or even disdain and that the organization itself has very little to do with the movement, even if many of its proponents are members.

From David Grabiner's Sabermetric Manifesto:

Bill James defined sabermetrics as "the search for objective knowledge about baseball." Thus, sabermetrics attempts to answer objective questions about baseball, such as "which player on the Red Sox contributed the most to the team's offense?" or "How many home runs will Ken Griffey, Jr. hit next year?" It cannot deal with the subjective judgments which are also important to the game, such as "Who is your favorite player?" or "That was a great game."

Sabermetrician often call into question traditional measures of baseball skill. For instance, batting average is considered to be a statistic of limited usefulness because it turns out to be a poor predictor of a team's ability to score runs. Typical sabermetric reasoning would say that runs win ballgames, and so a good measure of a player's worth is his ability to help his team score more runs than the opposing team.

Accordingly, sabermetric measures - such as Bill James's Runs created and Win shares or Pete Palmer's Total player rating - are usually phrased in terms of either runs or team wins; a player might be described as being worth 54 runs more than an average player at the same position over the course of a full season, for example.

Sabermetrics is concerned both with determining the value of a player in a season gone by, and with trying to predict the value of a player in the future based on his past performances. These are not the same thing. For example, a player with a high batting average one year may have been very valuable to his team, but batting average is known to be a volatile stat and relying on it to remain high in future years is often not a good principle. A sabermetrician might argue that a high walk rate is a better indication that a player will retain his value in the future.

While this area of study is still in development, it has yielded many interesting insights into the game of baseball, and in the area of performance measurement generally. Of course it has often led to just as many questionable conclusions, particularly concerning the value of a prolific base-stealer.

Some sabermetric measurements have entered mainstream baseball usage, especially OPS (on-base plus slugging) and, to a lesser extent, WHIP (walks plus hits per inning pitched).

Examples of Sabermetric Measurements

On-base plus slugging (OPS)
Runs created
Pythagorean expectation
Total player rating
Equivalent average (EQA)
Peripheral ERA (PERA)
Defense Independent Pitching Statistics (DIPS)
Secondary average
Value over replacement player (VORP)
Walks plus hits per inning pitched (WHIP)
Win shares

Major Proponents of Sabermetrics

Billy Beane has been the general manager of the Oakland Athletics since 1997. Although not a public proponent of sabermetrics, it has been widely noted that Beane has steered the team during his tenure according to some sabermetric principles: Batters should try to get walks, traditional defensive statistics (such as errors and fielding percentage) are less important than people think, pitchers should be able to strike out batters, spending amateur draft picks on high school pitchers is a bad use of resources, etc. What's remarkable about this is that so few other teams in baseball apply these principles, thus making the Athletics the first test case for sabermetrics in action. In 2003, Michael Lewis published Moneyball, a book about Beane and how his approach to running the Athletics works. In recent years, Beane assistants J. P. Ricciardi and Paul DePodesta have been hired as general managers for the Toronto Blue Jays and the Los Angeles Dodgers (though DePodesta was fired after two seasons of questionable trades and signings).

Don Daglow and Eddie Dombrower are baseball simulation game designers whose sabermetrics-based games have introduced "new statistics" to expanded audiences. They are best known for Intellivision World Series Baseball (1983) and Earl Weaver Baseball (1987). Daglow also designed Baseball (1971), Tony La Russa Baseball (1991) and Old Time Baseball (1995). Patrick Mondout created the first set of data disks for Earl Weaver Baseball (predating Electronic Arts' own efforts with Stats Inc. by a full year) and later created this website.

Bill James is widely considered the father of sabermetrics due to his extensive series of books, although a number of less well known SABR researchers in the early Super70s provided a foundation for his work. He began publishing his Baseball Abstracts in 1977 to study some questions about baseball he found interesting, and their eclectic mix of essays based on new kinds of statistics soon became popular with a generation of thinking baseball fans. He discontinued the annual Abstracts after the 1988 edition, but continued to be active in the field. His two Historical Baseball Abstract editions and Win Shares book have continued to advance the field of sabermetrics, 25 years after he began. In 2002 James was hired as a special advisor to the Boston Red Sox. Those who point to the Red Sox World Series victory two years later as validation of sabermetrics should curb their enthusiasm. The Red Sox had the second-highest payroll that year.

Rob Neyer is a columnist for ESPN's web site who has espoused sabermetrics since the mid-1990s. He has authored or co-authored several books about baseball including with Bill James, and his ESPN website page focuses on sabermetric methods for looking at baseball players' and teams' performance.

David Smith founded Project Retrosheet in 1989, with the objective of computerizing the box score of every major league baseball game ever played in order to more accurately collect and compare the statistics of the game. Although Smith is most of all an historian, the opportunity to apply sabermetric analysis to the data in order to better understand baseball's history, players and records is the driving motivation behind the all-volunteer project.

John Thorn and Pete Palmer are the authors most often mentioned along with Bill James as having popularized sabermetrics. Thorn is a noted baseball historian, while Palmer is by profession a statistician, although each has deep knowledge in the specialty of the other. They collaborated on two books that present sabermetric statistics and readable, common-sense explanations for why it's worth thinking about them: The Hidden Game of Baseball and the series of baseball encyclopedias called Total Baseball, with David Pietrusza and the late Michael Gershman. They also include the mathematical formulae for the hard-core statisticians, but the strength of their books is the accessibility of the statistics for everyday baseball fans. Thorn, Palmer and Gershman provided the statistics and analysis for the Tony La Russa Baseball series of computer games.

Earl Weaver, former manager of the Baltimore Orioles, would vociferously deny any such statistical leanings, and say his baseball strategy is based on "common sense." Nevertheless, his use of sabermetric-like methods is well-documented. Weaver was the first baseball manager to start keeping stats about how each of his batters did against each pitcher in the league, and the corresponding stats for each Orioles pitcher against each American League hitter, writing the statistics by hand on index cards and then hiring a college student to collate them. This kind of situational statistical study is one of the core concepts of sabermetrics. Thorn and Palmer specifically identify a number of ways in which Weaver's strategies reflected sabermetric principles in their books, which identify the eras in which Weaver's "God Bless the Three Run Homer" philosophy was in fact statistically justified. The computer game Earl Weaver Baseball had artificial intelligence based on Weaver's statistical principles.