Statistics are a very important part of following baseball. They help fans and coaches keep track of a particular player's performance. There are three main categories of statistics: batting, pitching, and fielding.
Batting average (abbreviated BA or AVG) is calculated by dividing a player's number of hits by his number of at bats. It is often used as a measure of consistency and is always written as a decimal to the thousandths place. An average BA is around .260, and a good BA is around .300.
Runs batted in (RBIs) is the number of times a player's hit directly causes a run to be scored. Let's say there is a runner on third base and the batter hits a single, allowing the runner on third to score a run, in this example, the batter is credited with an RBI.
Runs are slightly different than RBIs, they are the number of times a player has scored a run. (In the above scenario, the runner on third who scored would be credited with a run.) Home runs are the number of times a player has hit a home run. Similarly, stolen bases are the number of times a player has stolen a base.
Pitching statistics are used to analyze a pitcher's performance. The five main pitching statistics are wins, earned run average (ERA), walks and hits per innings pitched (WHIP), strikeouts, and saves.
A win is credited to the pitcher who was pitching when his team scored the winning run(s). For example, if a pitcher was pitching during the inning where his team scored three runs to win the game, he would get the win. If the team loses and regains the lead, and ends up winning, the pitcher who was pitching when the second lead was gained would get the win. Additionally, for a starting pitcher to qualify for a win, he must have pitched five or more consecutive innings.
Earned run average (ERA) is calculated by dividing the number of earned runs a pitcher has given up, by the number of innings he has pitched, and then multiplying this quotient by nine. It indicates how effectively a pitcher can prevent runs from being scored. It is written as a decimal to the hundredths place. An average ERA is around 4.00, while a good ERA is around 3.00 or under.
Walks and hits per innings pitched (WHIP) is calculated as its name suggests: by adding up the number of walks and hits a pitcher has given up, then dividing that number by his number of innings pitched. It indicates how effectively a pitcher can keep runners from reaching base, and is written as a decimal to the hundredths place. An average WHIP is around 1.30, while a good WHIP is around 1.10 or under.
Saves are statistics used to measure the performance of relief pitchers and closers. They are different from wins, as saves deal with the preservation of a lead and not the gaining of one. To qualify for a lead, a relief pitcher's team must be winning by three or fewer runs. If the lead is only one run, the tying run must be on-deck, at bat, or on a base. The pitcher must also pitch three or more innings.
Errors are the number of times a player messes up a play that he would have otherwise completed. Errors are often seen as below the expectation for a player's level of ability. For example, if a fielder in the MLB caught a ball but it slips out of his glove, that could count as an error since his level of ability indicates that he should have been able to hold onto it.
Double plays measure a team's performance. It is the number of times fielders on a team were able to make two outs in one play.