Fielding Independent Pitching (or FIP) is a metric designed to give us information about pitcher performance. FIP measures the events that are directly under a pitcher’s control: strikeouts, walks, and home runs. From there, a calculation is used to scale these events to a number very similar to the one you’ll find for ERA. It is a “rate” statistic, that resembles how many runs a pitcher might give up per nine innings, given these peripherals. So basically it is a pitcher’s ERA if the team’s defense is not factored in.
When looking at how well a pitcher’s season went, don’t just look at his record and ERA, as those stats might be valuable for the most part, but to see a pitcher’s true identity in the season, look at stats like his FIP, WHIP, K/9, etc. Sometimes when a pitcher has a bad season and his ERA is through the roof, don’t automatically think he is invaluable because his FIP might be lower. For example: Brandon McCarthy this year in 2014 had a record of 10-15 with a .405 ERA, but his FIP was posted at 3.55, as the Yankees and D-backs were no better than average on defense. This is also true for a pitcher who put up good numbers the previous season, as the player’s FIP might had been higher than his ERA, and that would mean that his teammates’ defense saved him some earned runs. For example: Alfredo Simon this year in 2014 had a record of 15-10 with a 3.44 ERA, but his FIP was 4.33, as Cincinnati won the Wilson Defensive Team of the year award. So FIP is a good indicator of a pitcher’s potential because they could be traded to another team with different defensive numbers at any moment.