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AM: Why the use of xFIP rather than just FIP? FIP is the actual Fielder Independent Pitching number, while xFIP is what is the expected Fielder Independent Pitching number. When we speak of a pitcher's Earned Run Average, (ERA) we never use the pitcher's xERA or the expected ERA, so why use that for FIP? Or, listing both such as FIP/xFIP could provide a measure of how well a pitcher is doing compared to what is expected. For instance, with Mitch Keller his FIP/xFIP would be 3.47 FIP/3.92 xFIP, therefore doing better than expected.

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author

FIP (and xFIP) is really used to compare to ERA in general. If a players FIP is better than their ERA, there may be room for improvement. Where as the FIP (or xFIP) is worst than the ERA, they may regress.

I prefer xFIP more just because it factors in what the league average home run rate is, so it could factor in if the pitcher is a bit unlucky. So, if their HR rate is 30%, and league average is 10-12%, then xFIP will factor that in, since likely the pitcher is getting a little unlucky (like Sean Sullivan in Greensboro). Or if a pitcher has like a 2/3% HR rate, they are probably getting lucky, and their xFIP will be more reflectant of that.

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Agree, 100%. The better and more predictive stat is xFIP. In fact, it would make a lot of sense if we never even looked at ERA, just xERA.

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author

For where it's available, yea I do like the expected metrics better, as long as they are used properly.

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Good points from both of you, thank you.

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