What is FIP?
FIP stands for Fielding Independent Pitching. It is a statistic meant to measure a pitcher’s effectiveness, taking plays that would involve the defense trying to field the ball out of the equation.
What is FIP?
FIP takes a pitcher’s strikeouts, walks, and home runs allowed and translates them into a number scaled to ERA.
Think of it as what the pitcher’s ERA should be, if the defense behind him turned batted balls into outs at a major-league average rate.
A good FIP, similar to a good ERA, is usually going to be one that is in the 2s or low 3s. The major-league leaders in FIP in 2012 were Gio Gonzalez (2.82), Felix Hernandez (2.84) and Clayton Kershaw (2.89). The pitchers who qualified for the ERA title with the worst FIPs in 2012 were Ervin Santana (5.63), Henderson Alvarez (5.18) and Ricky Romero (5.14).
How is it used?
FIP serves two primary purposes.
For one, it can show which pitchers were most and least effective at the things they controlled over a given time period.
The other thing that FIP can do is provide a clue that there are circumstances beyond a pitcher’s control impacting his performance, such as the quality of his defense, a propensity to allow a high or low rate of a batted-ball type (line drives, ground balls, fly balls), or good/bad luck.
Pitchers with season-long FIPs higher than their ERAs are often considered likely to decline in performance.
In 2011, there were 10 ERA-title qualifiers with a FIP that was at least .65 points higher than their ERA. Of those 10, nine had their ERA increase in 2012.
Similarly, pitchers with FIPs lower than their ERAs are often considered bounce-back candidates, though only five of nine 2011 ERA-title qualifiers with FIPs at least .65 points lower than their ERAs had their ERA decrease in 2012 (most notably Brandon Morrow, Ryan Dempster, and Zack Greinke).
Pitcher's yearly FIPs can be found at Fangraphs.com You can also listen to an explanation of the stat here