Glossary of Pitching Statistics Hitting | Fielding Linear Weights  KLWTS=              H-HR BIP%=  --------     Opponent's batting average on Balls Put In Play          3*IP-SO-DP BIP% vs Team = BIP%-Team BIP% A pitcher's ability to prevent hits on Balls Put In Play,                                                          independent of team defense.               PA ERA ERA+=   ---------  * 100   A player's ERA Park Adjusted and compared to the league average               Lg ERA FIP% - Fielding Independent Pitching - (HR*13+(BB-IBB+HB)*3-K*2)/IP + F Where F is a league-dependent factor used to make the stat resemble ERA. The 2006 factors are 3.22-NL and 3.26-AL.                         ERA+         Simpler and more accurate than PR in accounting for a pitcher's IP*ERA+ = IP * (  ------ - 1 )   longevity and effectiveness.  In my Top 100 List, I divide it by 3 to                            100           make it close to DPOR, allowing for good hitter/pitcher comparisons.         BB+SO+3*HR P%=    ---------           Rough percentage of a team's defense made up by ONLY pitchers          BB+H+3*IP              Regular Season ERA PERA+     --------------------------  * 100 Measures how much a pitcher stepped up or                Postseason ERA                choked during the playoffs. PLWTS - .47*1B + .78*2B + 1.09*3B + 1.4*HR + .33*(BB+HB) - .26*(AB-H-GIDP)-.72*GIDP In our Pitcher Stats section, we do not include stolen base data in our calculation. This is primarily because we do not have it handy, although it could be a blessing in disguise as many pitchers don't have a huge effect on basestealing effectiveness.        IP PR =  --- * (Lg ERA- ERA)  Pitching Runs- Runs saved beyond what a league average pitcher         9                                                      would save. PR+ Adjusted Pitching Runs- Pitching Runs adjusted for home ballpark effects Park = PR - PR+  Quantifies the home ballpark effect for a pitcher's entire career:                           Positive = Pitcher's Parks, Negative = Hitter's Parks                 R-ER UER/IP= -------     Unearned runs allowed per inning pitched                  IP WAT Original Formula: WAT= Decisions * (Pitcher W%-Team W%)    Wins Above Team Total Baseball jazzed it up for reasons that I do not find clear: WAT= Decisions * (Pitcher W%-Team W%)                    -----------------                   2 - 2 * Team W% WAT/D= Pitcher W% - Team W%   Allows for career "ability to win" comparisons between players                                                       with disparate career innings pitched.