## What is ERA?

**ERA** stands for Earned Run Average, and is one of the most important metrics used to measure a pitcher’s performance in baseball. It is the average number of earned runs a pitcher gives up per nine innings of work. A pitcher’s ERA is calculated over the course of an entire season, or over a number of seasons if the pitcher has been playing for a while. ERA is one of the most important statistics when evaluating a pitcher’s performance, as it can give an indication of how they are performing overall.

## What is an earned run?

An **earned run** is any run that a pitcher gives up due to their own pitching. This means that any run that is scored as a result of errors, passed balls, etc., is not considered an earned run. The earned run average is calculated by dividing the total number of earned runs by the total number of innings pitched.

## How is ERA calculated?

A pitcher’s ERA is calculated by dividing the total number of earned runs allowed by the total number of innings pitched. The formula for ERA is as follows:

- ERA = (Earned Runs / Innings Pitched) x 9

For example, if a pitcher has given up 10 earned runs in 60 innings pitched, their ERA would be:

- (10 / 60) x 9 = 1.5

This means that the pitcher has an ERA of 1.5, which is considered to be very good.

## What is a good ERA?

A **good ERA** is typically considered to be below 3.00. This means that the pitcher is allowing fewer than three earned runs per nine innings pitched. An ERA of 3.00 or lower is generally considered to be excellent, while an ERA of 4.00 or higher is considered to be poor.

## What factors affect a pitcher’s ERA?

There are a number of factors that can affect a pitcher’s ERA, including:

- The quality of the opposition
- The pitcher’s control
- The pitcher’s ability to get hitters out
- The pitcher’s luck (or lack thereof)

The quality of the opposition is particularly important, as a pitcher who is facing a weaker team will typically have a lower ERA than one who is facing a strong team.

## What is an ERA+?

An **ERA+** is a statistic that is used to compare a pitcher’s ERA to the league average. It is calculated by taking the pitcher’s ERA and dividing it by the league average ERA, then multiplying it by 100. This gives a number that indicates how much better or worse the pitcher is performing than the league average.

For example, if a pitcher has an ERA of 3.00 and the league average ERA is 4.00, their ERA+ would be:

- (3.00 / 4.00) x 100 = 75

This means that the pitcher is performing 25% worse than the league average.

## What is FIP?

FIP stands for Fielding Independent Pitching, and is an advanced statistic that attempts to measure a pitcher’s performance more accurately than ERA. It takes into account the number of walks and strikeouts, as well as the number of home runs allowed. FIP is calculated by taking the number of walks, strikeouts, and home runs allowed, and dividing it by the number of innings pitched. The formula for FIP is as follows:

- FIP = (Walks + Strikeouts + Home Runs) / Innings Pitched

## What is xFIP?

xFIP stands for Expected Fielding Independent Pitching, and is a variant of FIP that attempts to normalize the home run rate. It does this by taking the average number of home runs allowed by pitchers around the league, and adjusting the pitcher’s home run rate to match. The formula for xFIP is as follows:

- xFIP = (Walks + Strikeouts + League Average Home Runs) / Innings Pitched

## Conclusion

A pitcher’s ERA is a key statistic that can give an indication of how they are performing in a given season. It is calculated by dividing the total number of earned runs allowed by the total number of innings pitched. ERA is typically considered to be good if it is below 3.00, while ERA+ and FIP/xFIP can be used to compare a pitcher’s performance to the league average.