"A pitcher's effectiveness is closely tied to the number of baserunners he allows and the number of strikeouts he gets. This table uses a rating system of K/BB + K/9IP - (BB+H)/9IP - HR/9IP. This formula is best used as an indicator of future performance of a pitcher. A pitcher may have a low era after 15-20 innings, but may not have been pitching as effectively as the era indicates. A look at this rating system will be a good way to tell if the pitcher will continue with the low era or will soon run into some trouble."
This is a metric that is screaming to be visualized. The visualization uses Lahman's Baseball Database to let users explore the relationship between the Pitcher Effectiveness Rating and the individual metrics that combine to make the rating. Users can drill into different eras over baseball's past and look for changes in the rating based on the pitchers age and the total number of innings pitched over a career.
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