Component ERA

Component ERA or ERC is a baseball statistic invented by Bill James. It attempts to forecast a pitcher's earned run average (ERA) from the number of hits and walks allowed rather than the standard formula of average number of earned runs per nine innings. ERC allows one to take a fresh look at a pitcher's performance and gauge if his results are more or less than the sum of its parts.

The formula for ERC as it appears in the 2004 edition of the Bill James Handbook:

${\displaystyle ERC=9*{(H+BB+HBP)*PTB \over BFP*IP}-0.56}$

where H is hits, BB is bases on balls (walks), HBP is hit by pitch, BFP is batters faced by pitcher, IP is innings pitched, and PTB is pitcher's total bases and is defined as:

${\displaystyle PTB=0.89*(1.255*(H-HR)+4*HR)+0.56*(BB+HBP-IBB)}$

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