Stat of the Week: APR

APR, or Adjusted Pitching Runs, measures the number of runs a pitcher prevented as compared to a league-average pitcher in a neutral park in the same number of innings. Derived from the pitching component of linear weights, or pitching runs, APR includes an adjustment for ballparks and is based on all runs allowed, not just the earned runs.

APR = L x IP – (R/PF)

Where “L” is the league average of runs per inning and “PF” is the park factor for the pitcher’s home park.