Baseball is filled with statistics, rules, and archaic terms that can often form what sounds like a foreign language. Sons of Sam Horn’s glossary provides a better understanding of these terms through straightforward definitions, clear explanations, and examples pulled straight from the baseball world. If there is anything you would like us to add to our glossary, please contact us.
Expected Fielding Independent Pitching
Expected fielding independent pitching, or xFIP, is a statistic used to measure only the events that the pitcher can control. It is calculated much like FIP, in that it relies on strikeouts, walks, and hit batsmen; however, xFIP differs in how it treats home runs allowed. Rather than including the actual home runs the pitcher allows, xFIP takes the fly balls allowed and multiplies that total by the league average home run to fly ball ratio. This normalizes the pitcher’s own HR/FB rate, taking any luck out of that figure.
How Is It Calculated?
Why Fly Balls?
The formula is nearly identical to FIP’s, with the fly balls and LgHR/FB% replacing the home runs allowed. This adjustment to FIP’s formula gives the pitcher a league-average amount of HR allowed relative to the amount of fly balls he allows to be put in play, taking any luck (good or bad) out of his HR total. This is done because HR/FB% can vary over short periods of time, including single seasons.
Things To Consider
- xFIP is a better predictive statistic than FIP, while FIP will give you a better idea of what actually occurred.
- Some pitchers will have career HR/FB% that are above or below the league average. Be sure to check for career-long trends before making assumptions about a particular pitcher.
- Ground ball pitchers tend to have higher HR/FB% since their fly balls tend to be mistakes left up in the zone that are hit harder.
- xFIP is not adjusted for park or league.
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