Saber 101: Fielding Independent Pitching
by Mike Rogers on Feb 4, 2010 6:51 PM EST
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PrintNearly a decade ago Voros McCracken shook the sabermetric landscape with the simple theory that much of what we thought of pitching is actually more about the defenders behind him than the pitcher itself. The seminal piece on Baseball Prospectus can be boiled down to one, oft-quoted line:
There is little if any difference among major-league pitchers in their ability to prevent hits on balls hit in the field of play.
Basically, McCracken found that pitchers really only control a few key things like strikeouts, walks, and home runs. If you just think about it, it does make sense. Should Justin Verlander be rewarded because Adam Everett is a vacuum at shortstop? Should Verlander be punished because Carlos Guillen was manning that spot behind him back in 2006? No, he shouldn't.
After the jump, I'll give you all the reasons you need to to not use ERA as a stick against which to measure pitchers again...
What is Fielding Independent Pitching?
Using the things we've come to accept that are in the pitcher's control, it builds an ERA replicator. The number that comes out is how a pitcher has actually pitched and is a much better predictor of future success than a pitchers ERA.
How does it work?
The formula applies weights to each of the strikeouts, walks, and homers that reflect their run value. You then add a constant (usually around 3.2, but it changes from year-to-year) that puts it on the ERA scale. It is a great stat to see how a pitcher is actually performing, regardless of what the pitchers actual ERA looks like.
Also, given that FIP is simple, there are chances that luck can skew things -- namely in the home runs column. But, that is where Expected FIP (xFIP) comes in. It normalizes the home runs a pitcher allows to the league average because there isn't a lot of evidence that a pitcher controls his home run rate entirely. He can control it, but like Batting Average on Balls In Play, it can range from year-to-year. xFIP attempts to correct for that.
Flaws in the system
Whether you want to consider this a flaw or not, it doesn't track that actual number of runs scored on a particular pitcher's watch. Whether we like it or not, runs score while Verlander is on the mound. Some are his fault, some aren't.
Why you should use it
Alex Remington's recap on FIP said it best:
Basically, the fundamental difference between old-school stats and new-school stats is that old-school stats measure what happened at the surface level — batting average, earned run average, wins. New-school stats try to measure each player's contribution to those surface stats, while filtering out the contributions of their teammates and the random fluctuations of chance.
That's what makes FIP better than ERA. Want to get an idea of whether a pitcher is awful? Check his FIP. If his FIP is lower than his actual ERA, it's indicating that he's pitched better than his ERA, and that his defense or luck might not be on his side.
Hey, if it's good enough for Zach Greinke or for Max Scherzer, isn't it good enough for us?
Resources
Fangraphs, as always, is the first stop for advanced metrics of this nature. Alex Remington's piece I linked to above was a nice jumping off point, as well.
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Is this generally not a good stat to use for sinker-ballers?
With an emphasis on contact and the loss of Ks in numerator, it would seem they would always outperform their FIP.
But
At the same time, they’re not giving up home runs or walks- so xFIP may be a better metric for them since it incorporates BABIP.
President, Vice President and Secretary of the Casey Crosby Fanclub.
Yes and no. It underrates them to a degree, but there is rewards for batted ball type — it’s just hidden in the data (a.k.a. sinker ballers rarely give up the long ball, thus, the biggest negative against them doesn’t come into play that often). For instance, Derek Lowe has a 3.79 FIP and he’s about as much of a sinker baller as they come.
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I wasn’t sure how much, if at all, I should touch on it in the article, but there is tRA for those that feel sinker-ballers don’t get enough love. Fangraphs has tRA on their pages but I prefer to support the originators and go to Statcorner for it.
The difference between tRA and FIP is simple: FIP is K’s, BB’s, HR’s and divided by innings pitched. tRA is based entirely on batted ball data. Each type of batted ball has a run value attached to it. If a pitcher gives up a ton of line drives (the most damaging type of batted ball) their tRA will be bad. A ground ball, however, is pretty much the same run value as non-home run fly balls
My recommendation, though, would be to look at tRA* when at all possible. It is basically their version of xFIP — it regresses some components that aren’t entirely in the pitchers control towards the league average. This helps ease out some of the luck-based tRA’s for the season.
Also, tRA stands for True Runs Allowed (I believe), and there for is a runs allowed measurement NOT AN ERA REPLICATOR like FIP. So, if you want to compare the two, you have to multiply tRA by 0.92 to put it to an ERA number. We do this because about 92% of all runs allowed are ‘earned runs.’
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
nice read...
This series is really helping me learn. I’m taking some things that I learn (or figure out based upon what I’ve read here) and apply it to other stats. So thanks Mike!
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That’s the plan! Glad you’re enjoying it.
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
I like math!
I just haven’t paid attention to sabermetrics for such a long time that I don’t know what the stats are, what they measure, and such things as “this number is average, this number is really good, this number is really bad” for each one.
Still, it’s nice that it is possible to enjoy baseball without a lick of math.
"While there's life, there's hope." --Cicero
the math is making baseball more fun for me...
staring at spreadsheets of numbers is reminding of how big a geek I am.
My Music: Now on last.fm!!
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This is me 100%. I started to get into prospects a bit and stumbled upon The Hardball Times and it changed my entire impression of baseball. Sabermetrics opened up avenues in the sport that I didn’t know existed and completely changed how much I love the sport.
The nerdery it’s brought out in myself has shocked me. I play around in Excel with numbers now a ton (for college basketball, hockey, college baseball … nearly everything now).
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
Same here
I remember buying the Baseball Prospectus for 2007 at NCFL Nationals (a debate tournament) and having my roommates laugh at me for literally spending hours reading it.
President, Vice President and Secretary of the Casey Crosby Fanclub.
The average FIP the last two seasons has been 4.32. It is right around the league average ERA. Since this is an ERA replicator, basically just think of it on the ERA scale.
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
that helps
The biggest problem I have with the newer stats tossed around is lack of a frame of reference. Once I have a basis for comparison, I’m fine.
"While there's life, there's hope." --Cicero
Well, feel free to ask. Numbers always need some sort of context, so I guess I should’ve done a better job at that in the wOBA and this article.
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
You can skip over the formula. Pretend it’s not there!
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
Aside: I remember when Voros's article appeared on Baseball Prospectus.
I thought: man, this is some crazy idea and I like it.
You are old school, my friend. I was about 5 years too late to the party.
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
So i'm trying to contextualize FIP by looking at Jeremy Bondermans FIP from season to season...
I can generally assume that (when healthy) Jeremy Bonderman is a better pitcher than what the score board may show. This assumption is based upon the fact that from season to season (besides the past 2 when he was injured) Bondo has posted a better FIP than ERA.
So just to make sure I’m understanding the stat right, am I correct in my assumption?
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You are correct. Bondo had a very fine K:BB ratio which always drove down his FIP’s. People lamented his first inning woes, but for the next 5-6 he was (generally) a shut down pitcher.
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
sweet.
now I have a stat to prove that does a pretty good job of summing up all that other stuff i was looking at individually.
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My Blog: Strike Three Mechanics
i need to really start proof reading.
or fully utilizing backspace.
My Music: Now on last.fm!!
My Blog: Strike Three Mechanics
The only problem I have
with FIP (and it’s not really a problem, per se) is that it skews towards strikeout pitchers. Or, more appropriately I suppose, guys who strike out a bunch and don’t give up many walks or homers. Granted, those are exactly the types of pitcher that you want, but in a given season you can have some weirdness associated with it (see Pavano, Carl). As I said, it’s not a “problem”, just a minor quirk.
that's kind of the definition of the stat though
If you create a stat that looks at the pitcher’s contribution to the game, it’s going to skew towards making outs the batter doesn’t put in play, putting runners on base and letting the ball go over the fence.
As to why those are included in the formula, which I suspect you know but just for anyone reading the comments, it’s because almost every other scenario that can happen after a pitcher throws the ball cannot be controled directly. So why would you credit or debit the pitcher for something out of his control?
Some pitchers do show the ability to outperform expectations consistently, which throws a small wrench in the assumptions, but for the majority of them the assumptions hold and FIP tells you just what a pitcher can and can’t do regardless of the seven guys behind him and one in front.
by Kurt Mensching on Feb 5, 2010 10:43 PM EST up reply actions
better to factor in contact rates?
Seems to me that it would be better to factor in the contact rate a pitcher has rather than rely only on HR, K & BB. Hits from balls in play cannot be controlled by a pitcher but a pitcher can control contact rates. If you had a measure that factored in contact rates and HR you might be fairer to ground ball pitchers.
If you had a measure that factored in contact rates and HR you might be fairer to ground ball pitchers.
I’m not sure I follow, since the batter would be making contact with the ball in order to have a ground ball. Contact rate and strikeout rate tend to overlap pretty decently, I think.
You might prefer tRA, which takes into batted ball type. For groundball pitchers, it might be better, but the batted ball type can vary a bit from year to year so I like FIP.
by Kurt Mensching on Feb 6, 2010 1:53 PM EST up reply actions
Excuse my ignorance!
Thanks. you will have to excuse my ignorance because having lived in Europe for the whole of my life apart from the past 5 years, I am relatively new to baseball!
But…I do see that FIP is truly fielding independent. I just don’t think it measures a pitcher’s worth because it doesn’t take into account non-HR hits. If it is true that there is little difference between pitchers in preventing hits from balls in play, then surely assessing how often balls are in play with a pitcher is needed. If strike out rates are related (the reciprocal?) to contact rates then I guess I see now why FIP appears to be a somewhat consistent measure in that it does take into account contact, albeit indirectly.
I see how tRA might be better, but having looked at it briefly, I wasn’t sure if it accounted for BB and K too….if not, seems to me you would need some amalgam of tRA and FIP.
The other thing I was thinking about was that FIP is an average based on 9 innings.
But if we’re trying to assess how useful a starting pitcher is, for example, we might want to know how long that pitcher typically lasts, which means that we might want to know how this measure varies across innings e.g. how different it is in the 1st versus the 6th inning. If I’m a manager (which obviously I’m not) it would be useful to know when I should pull a pitcher during a game! Am I way off?
don't feel ignorant!
this stuff is all pretty new to most baseball fans, it’s why we’re having a series to discuss these types of things!
As for your thoughts, that is why I think it’s important to look at several statistics, both saber and traditional.
ERA tells you what happened, so it has value. But it might not predict what will happen and depends on the defense.
FIP or tRA are better predictors, so they’re good to look at to make a better guess what to expect in a neutral environment.
Knowing the innings pitched helps put it all into perspective.
As for deciding when to change pitchers, that’s where managing is a feel or experience thing. I don’t know that you want to rely on stats to decide that. Maybe something basic like “our guy struggles in the sixth and the matchups do not look favorable” or something. But if he’s cruising, maybe you just keep him in.
by Kurt Mensching on Feb 6, 2010 4:56 PM EST up reply actions
heck, I grew up with baseball
But I don’t have a handle on all the newer stats being used now. It’s one of those things that is very easy to not keep up with and then you try not to drown in a flood of acronyms. :)
"While there's life, there's hope." --Cicero
I’m not sure what you would want out of a stat then. What do you want your pitcher to do the most? Strike out every batter he faces, no?
My old blog is Tigers By The Numbers.
Now I write at Bless You Boys.
Like music? See what I'm listening to at my Last.fm account.
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