Most of the stats discussed on this blog are either from Baseball-Reference.com or Fangraphs.com.

Here are a few of the stats quite commonly mentioned:

  • WAR stands for Wins Above Replacement and is a measure of how many wins a player was worth as compared to a replacement-level player. The exact method of determining WAR is complex, and it differs between B-R.com and Fangraphs. Commonly on this site, then, you may see the designations bWAR and fWAR if the numbers are drawn from one of those two particular web sites.
  • OPS is on-base percentage plus slugging percentage. OPS+ is a normalized version of OPS that takes into account both the league-wide average OPS as well as the player’s home ballpark. A value of 100 is considered league-average, while over 100 is better than average.
  • ERA+ is similar to OPS+ in that it has been normalized to the league-wide average ERA and the player’s ballpark. 100 is average, while over 100 is better than average.
Game Score (explanation taken from B-R page here):
  • This is a value created by Bill James that evaluates how good a pitcher’s start was.

    Start with 50 points. Add 1 point for each out recorded, (or 3 points per inning). Add 2 points for each inning completed after the 4th. Add 1 point for each strikeout. Subtract 2 points for each hit allowed. Subtract 4 points for each earned run allowed. Subtract 2 points for each unearned run allowed. Subtract 1 point for each walk.

Please add any requests in the comments below for more terms to be explained here.