Friday, October 07, 2005
The value of FIP and xFIP
I can't county how many times I've heard the statement "Such and such is a great pitcher because they had an ERA of 2.55 this year." While in many cases, that can be correct: Pedro Martinez, Roger Clemens, Randy Johnson. Now, I'll give you a list of AL rookie pitchers and you tell me who doesn't fit:
Joe Blanton
Huston Street
Gustavo Chacin
Felix Hernandez
If you said Felix Hernandez, then you are headed in the same direction as I. Felix's sabermetric numbers made these other guys look silly. The secret? Strikeouts and groundballs!
Joe Blanton:
Looked good in his rookie season. Had a solid ERA of 3.53. Case closed? Not hardly. His FIP is a lofty 4.47 and his xFIP is even higher at 4.84. The reason? He was a moderate groundball pitcher with a G/F ratio of 1.15, but he only struck out 116 in 201 innings and flyballs left the yard at 9.2%, which is about 4% lower than average. He got lucky.
Gustavo Chacin:
Solid rookie campaign. An okay 3.72 ERA over the full season. Again, looking at his FIP (4.30) and xFIP (4.89) you see that he really was lucky to have a pretty good defense playing behind him. He is a groundball/flyball neutral pitcher with a ratio of 0.99. But, like Blanton, his strikeout numbers are quite underwhelming. He only struck out 121 in 203 innings. Also, he was quite lucky with his flyballs, only having 7.8% go for home runs.
Huston Street:
Had one of the strongest rookie seasons in the AL by a pitcher. However, his stats are quite disparate. His raw ERA of 1.72 looks very impressive, considering the kid was in the closer role and faced pressure situations regularly. However, he had a pretty good defense playing behind him (FIP of 2.79) and was tremendously lucky with flyballs. Only 3.5% were home runs! This causes his xFIP to jump to 3.85. While a 3.85 ERA isn't bad, it certainly looks a lot worse than a nice shiny ERA of 1.72.
Felix Hernandez:
This kid was everything we could have hoped for and more. His 2.67 ERA looks great, and his sabermetric numbers hold up equally well. We know the M's defense is okay, so that helped him out a bit (FIP of 2.90). Now, if you normalize his flyballs, his xFIP remains constant at 2.90 because he allowed 11.1% of his flyballs to leave the yard. His secret? Not allow many flyballs. Of the 271 outs Felix was responsible for, only 45 were flyouts! He had a ridiculous 3.31 G/F ratio and struck out 8.22 per 9 innings. Why did scouts drool over this kid? For these kinds of numbers exactly.
They say that FIP and xFIP are very good predictors of future success. I think we can count on seeing Felix numbers regress a little bit, simply for the fact that hitters will have time to study him, but if he stays with that kind of G/F ratio and increase his strikeouts just a little, he could be one of the best pitchers of all-time.
Bonus:
Here are some more pitchers that had good years in terms of their ERA, but their sabermetric numbers are more telling. The first number is raw ERA, second number is FIP, third number is xFIP:
Jorge Sosa: 2.55/4.33/5.13
Aaron Small: 3.20/3.92/5.06
Jarrod Washburn: 3.20/4.39/5.01
You don't need stats to tell you that the above is true. But Jesus you're right, it helps back things up for people that don't watch/know much about baseball.
