Plate Discipline (O-Swing%, Z-Swing%, etc.)

Plate Discipline statistics tell us a wide number of things about pitchers: how effective they are at attacking the zone, how often they get hitters to chase on pitches (both inside and outside the zone), how often they throw a first-pitch strike, etc. There are a wide number of these stats:

O-Swing%: The percentage of pitches a batter swings at outside the strike zone.
Z-Swing%: The percentage of pitches a batter swings at inside the strike zone.
Swing%: The overall percentage of pitches a batter swings at.
O-Contact%: The percentage of pitches a batter makes contact with outside the strike zone when swinging the bat.
Z-Contact%: The percentage of pitches a batter makes contact with inside the strike zone when swinging the bat.
Contact%: The overall percentage of a batter makes contact with when swinging the bat.
Zone%: The overall percentage of pitches a batter sees inside the strike zone.
F-Strike% – The percentage of first pitch strikes.
SwStr%: The percentage of total pitches a batter swings and misses on.

FanGraphs carries plate discipline statistics based on both Baseball Info. Solutions (BIS) data as well as Pitch f/x data. There are some minor differences between the two systems. The Pitch f/x section presents raw Pitch f/x data broken down according to defined baselines, while the BIS section takes the Pitch F/x data and uses human scorers to modify classifications.

Here are the batter plate discipline leaderboards according to BIS data, and here are the same leaderboards according to PITCHf/x data.

Context:

Please note that the following chart is meant as an estimate, and that league-average for all of these stats varies on a year-by-year basis. To see the league-average plate discipline stats for every year from 2002 to the present, check the FanGraphs leaderboards.

Stat Average
O-Swing 30%
Z-Swing 65%
Swing 46%
O-Contact 68%
Z-Contact 88%
Contact 81%
Zone 45%
F-Strike 59%
SwStr 8.5%

Things to Remember:

● These statistics are useful for evaluating hitters and pitchers, with SwStr% being especially important when looking at pitchers.

● Swinging strike percentage (SwStr% — swinging strikes per pitch) should not be confused with whiff rate (swinging strikes per swing).

Links for Further Reading:

Plate Discipline Stats – FanGraphs

Introducing Plate Discipline Stats – Hardball Times

Plate Discipline Stats in Action – Hardball Times