Baseball statistics play an important role in evaluating the progress of a player or team.
In baseball statistics, on-base percentage (OBP) measures how frequently a batter reaches base. An official Major League Baseball (MLB) statistic since 1984, it is sometimes referred to as on-base average (OBA), as it is rarely presented as a true percentage.
In sports analytics, sabermetrics is the empirical analysis of baseball, especially baseball statistics that measure in-game activity. Sabermetricians collect and summarize the relevant data from this in-game activity to answer specific questions. The term is derived from the acronym SABR, which stands for the Society for American Baseball Research, founded in 1971. The term "sabermetrics" was coined by Bill James, who is one of its pioneers and is often considered its most prominent advocate and public face.
In baseball statistics, slugging percentage (SLG) is a measure of the batting productivity of a hitter. It is calculated as total bases divided by at-bats, through the following formula, where AB is the number of at-bats for a given player, and 1B, 2B, 3B, and HR are the number of singles, doubles, triples, and home runs, respectively:
Runs created (RC) is a baseball statistic invented by Bill James to estimate the number of runs a hitter contributes to their team.
Citizens Bank Park is a baseball stadium located in Philadelphia, Pennsylvania, in the city's South Philadelphia Sports Complex. It is the ballpark of Major League Baseball's Philadelphia Phillies. The stadium opened April 3, 2004, and hosted its first regular season baseball game on April 12 of the same year, with the Phillies losing to the Cincinnati Reds, 4–1. It is named after Citizens Financial Group.
In baseball statistics, walks plus hits per inning pitched (WHIP) is a sabermetric measurement of the number of baserunners a pitcher has allowed per inning pitched. WHIP is calculated by adding the number of walks and hits allowed and dividing this sum by the number of innings pitched.
In baseball, value over replacement player is a statistic popularized by Keith Woolner that demonstrates how much a hitter or pitcher contributes to their team in comparison to a replacement-level player who is an average fielder at that position and a below average hitter. A replacement player performs at "replacement level," which is the level of performance an average team can expect when trying to replace a player at minimal cost, also known as "freely available talent."
In baseball, defense-independent pitching statistics (DIPS) is intended to measure a pitcher's effectiveness based only on statistics that do not involve fielders. These include home runs allowed, strikeouts, hit batters, walks, and, more recently, fly ball percentage, ground ball percentage, and line drive percentage. By focusing on these statistics and ignoring what happens once a ball is put in play, which – on most plays – the pitcher has little control over, DIPS claims to offer a clearer picture of the pitcher's true ability.
In baseball, the dead-ball era was the period from approximately 1900 to 1920. This era was characterized by low-scoring games and a lack of home runs; league batting averages dropped as low as .239 in 1908, producing the lowest league run average in history, with teams averaging only 3.4 runs per game. Teams played in spacious ballparks that limited hitting for power; as a further hindrance to scoring, the ball used then, compared to modern baseballs, was "dead" both by design and from overuse. In addition, ball scuffing and adulteration by pitchers, notably the spitball, was not against the rules during this period.
In baseball statistics, batting average on balls in play is a measurement of how often batted balls result in hits, excluding home runs. It can be expressed as, "when you hit the ball and it’s not a home run, what’s your batting average?" The statistic is typically used to evaluate individual batters and individual pitchers.
Adjusted ERA+, often simply abbreviated to ERA+ or ERA plus, is a pitching statistic in baseball. It adjusts a pitcher's earned run average (ERA) according to the pitcher's ballpark and the ERA of the pitcher's league.
This is an alphabetical list of selected unofficial and specialized terms, phrases, and other jargon used in baseball, along with their definitions, including illustrative examples for many entries.
Base runs (BsR) is a baseball statistic invented by sabermetrician David Smyth to estimate the number of runs a team "should have" scored given their component offensive statistics, as well as the number of runs a hitter or pitcher creates or allows. It measures essentially the same thing as Bill James' runs created, but as sabermetrician Tom M. Tango points out, base runs models the reality of the run-scoring process "significantly better than any other run estimator".
In baseball statistics, run average (RA) refers to measures of the rate at which runs are allowed or scored. For pitchers, the run average is the number of runs—earned or unearned—allowed per nine innings. It is calculated using this formula:
In baseball statistics, earned run average (ERA) is the average of earned runs allowed by a pitcher per nine innings pitched. It is determined by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine. Thus, a lower ERA is better. Runs resulting from passed balls, defensive errors, and runners placed on base at the start of extra innings are recorded as unearned runs and omitted from ERA calculations.
In baseball, wOBA is a statistic, based on linear weights, designed to measure a player's overall offensive contributions per plate appearance. It is formed from taking the observed run values of various offensive events, dividing by a player's plate appearances, and scaling the result to be on the same scale as on-base percentage. Unlike statistics like OPS, wOBA attempts to assign the proper value for each type of hitting event. It was created by Tom Tango and his coauthors for The Book: Playing the Percentages in Baseball.
Win Shares is a book about baseball written by Bill James and Jim Henzler, published by STATS, Inc. in 2002. The book explains how to apply the concept of sabermetrics to assess the impact of player performance in a combination of several areas including offensive, defensive and pitching to the overall performance of their team. The resulting "Win Share" also takes into account factors such as the era in which the player was active to allow easy comparisons between players from different eras. The book focuses primarily on the many formulae involved in computing the final number of win shares accumulated, as well as presenting lists of players ranked in various ways using the rating.
In sports, park effects are the unique factors of each stadium/arena which impact a game's outcome. These effects are broken down into different components and used in advanced statistical analysis. While most sports have regulation-sized fields, some sports/leagues such as Major League Baseball (MLB) and NCAA Hockey, allow for varying field of play dimensions. The most common example of a park effect is a baseball stadium's batting park factor, but there exists other factors that impact all sports. Every stadium throughout the world has its own unique effects that impact the sports played there.
In baseball statistics, exit velocity (EV) is the estimated speed at which a batted ball is travelling as it is coming off the player's bat. Batters generally aim for a higher exit velocity in order to give opposing fielders less time to react and attempt a defensive play; however, many batters are still able to accrue hits without a high exit velocity. A pitcher will attempt to limit the exit velocity on the opposing batter's contact in order to allow the fielders or themself a better chance at making an out.
