## Batting Terms

- AVG: Batting Average. A measure, represented by a decimal, of how often a batter gets a hit.
- BABIP: Batting Average on Balls In Play. A measure of how many balls a batter puts in play fall for hits. Variation in BABIP can dramatically impact a player's AVG.
- BB%: Walk rate. Calculated by number of walks a player has, divided by plate appearances.
- Contact%: The percentage of pitches a batter makes contact with when he swings.
- F-Strike%: A measure of how often a batter falls behind in the count 0-1, whether it be by a called strike or a swinging strike.
- FB%: Fly ball percentage, which measures the portion of balls in play that a batter hits for fly balls.
- GB%: Ground ball percentage, which measures the portion of balls in play that a batter hits for ground balls.
- HR/FB: Home run to fly ball rate. Calculated by number of home runs divided by the number of fly balls. Each player establishes their own baseline, and sudden spikes or decreases may be indicators for regression.
- ISO: Isolated Power. A measure of a player's "raw power", and is generally calculated by subtracting AVG from SLG. League average in 2013 was .143.
- K%: Strikeout rate. Calculated by number of strikeouts a player has divided by plate appearances.
- LD%: Line drive percentage, which measures the portion of balls in play that a batter hits for line drives.
- O-Contact%: Contact rate on pitches outside of the strike zone.
- O-Swing%: Swing rate on pitches outside of the strike zone.
- OBP: On Base Percentage. A measure of how often a batter gets on base.
- Spd: Speed score. Developed by Bill James, and attempts to measure a player's entire baserunning ability. League average in 2013 was 4.4.
- Swing%: Percentage of pitches a batter swings at.
- SwStr%: Swinging strike percentage. A measure of how often a player swings and misses at a pitch, and is calculated by whiffs divided by pitches seen.
- Z-Contact%: Contact rate on pitches inside the strike zone.
- Z-Swing%: Swing rate on pitches inside the zone.
- Zone%: Percentage of pitches that a batter sees that are inside the strike zone.

## Pitching Terms

- BABIP: Batting Average On Balls In Play. A measure of how many balls a pitcher allows to be put in play fall for hits. Studies have shown that pitchers have little control over their own BABIP.
- BB%: Walk percentage. Measures what percentage of batters a pitcher walks.
- BB/9: Walk rate, per nine innings.
- Contact%: The percentage of pitches that a batter made contact on.
- ERA: Earned run average. Measures the number of runs a pitcher allows per nine innings.
- F-Strike%: Percentage of batters in which the pitcher gets ahead in the count 0-1, or how often the pitcher gets the first strike.
- FB%: Fly ball percentage, which measures the portion of balls in the play that the pitcher has allowed that are fly balls.
- FIP: Fielding independent pitching. Attempts to measure pitcher performance by estimating ERA based on factors that are in the sole control of the pitcher. Home run rate is assumed to be league average. FIP uses home runs, walks, hit by pitches, and strikeouts.
- xFIP: Expected fielding independent pitching. Instead of using the number of home runs the pitcher has allowed, the number of home runs is estimated using league average HR/FB rate and the fly ball rate of the individual pitcher.
- GB%: Ground ball percentage, which measures the portion of balls in the play that the pitcher has allowed that are ground balls.
- HR/FB: Home runs to fly ball rate. Calculated by number of home runs divided by number of fly balls. K/9: Strikeout rate. Calculated by the number of strikeouts per nine innings.
- K%: Strikeout percentage. Measures the percentage of batters that the pitcher strikes out.
- LD%: Line drive percentage, which measures the portion of balls in play that the pitcher has allowed that are line drives.
- LOB%: Strand rate, or "left on base percentage". Measures the percentage of batters that a pitcher allows on base, but do not score.
- O-Contact%: Contact rate on pitches outside the strike zone.
- O-Swing%: Swing rate on pitches outside the strike zone.
- Swing%: Percentage of pitches a batter swings at.
- SwStr%: Percentage of pitches that the batter swings and misses on. Calculated by by whiffs divided by pitches thrown.
- WHIP: Walks and hits per innings pitched. Used to measure the number of base runners a pitcher allows per inning.
- Z-Contact%: Contact rate on pitches inside the strike zone.
- Z-Swing%: Swing rate on pitches inside the strike zone.

*The glossary will be continually updated to reflect new terms introduced in articles as they are published.*