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.
Adjusted on-base percentage plus slugging, or OPS+, normalizes OPS across leagues while accounting for park factors. The statistic is expressed on a scale in which 100 is average and each point above 100 represent a percentage point above average, while a point below 100 represents a percentage point below average. Since OPS+ is normalized for both league and park, we can use it to not only compare players from the American and National leagues, but also across eras.
How Is It Calculated?
Before calculating OPS+, it is important to understand the main components of the statistic: on-base percentage (OBP), slugging percentage (SLG), and on-base plus slugging (OPS). OBP measures how often a player does not make an out, which should be the goal of every batter as it prolongs the game for the offense and increases the likelihood of scoring runs. It is calculated as follows:
SLG is the total bases a hitter averages per at-bat. It measures the power a player exhibits at the plate:
Finally, OPS is a simple statistic meant to give a quick and easy picture of a batter’s profile by adding the two previous statistics together:
So, What’s the Calculation?
lgOBP and lgSLG are the league average OBP and SLG, respectively, and they are each park adjusted. Pitchers are removed from the lgOBP and lgSLG calculations so as to not weigh the averages down.
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