The DRaysBay Stats Guide 2.0
by R.J. Anderson on Jan 28, 2010 2:57 PM EST
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PrintA little over a year ago I wrote the first DRB Stats Guide which has its fair share of mileage. So today I offer a new one in a different format.
What stats should I use to evaluate pitching?
On a game to game basis:
- Strikeouts
-Walks
- Home runs (to a lesser extent, explained below)
- Ground balls
- Swinging strikes
Those numbers play into FIP (which is like ERA, only it strips the defensive aspect from the equation) and xFIP (which is FIP, which strips the home run luck aspect from the equation) as well as tRA. Those are the three quick references for allowed run estimators. Home runs are tricky because research has found that most pitchers will regress towards ~11% home runs on all fly balls given up. That means, a number that far exceeds (or undercuts) 11% is probably a combination of luck and/or environment more so than skill.
You can find the majority of those stats at any ol' place (like Baseball-Reference) but FanGraphs features batted ball data as well as plate disciple data, which includes Contact% and handy averages.
I highly recommend reading Dave Cameron's guide to evaluating pitchers. It's dated, but still good.
What stats should I use to evaluate hitting?
If you hate using wOBA, then:
- BB%
- SO%
- ISO
- BABIP
Otherwise, just use wOBA. It correlates closely with runs scored and weighs the value of OBP better than OPS does (one point of OBP is worth 1.8 of SLG).
What stats should I use to evaluate fielding?
- UZR
- Plus/Minus
What stats should I avoid using as measure of value?
- BA
- RBI
- W/L
- WHIP
- BAA
- CERA
What are appropriate sample sizes for single season numbers?
These come from a Pizza Cutter post that went lights out when MVN did, but the figures represent the place where R = .5:
50 PA - swing percentage
100 PA - contact rate, response bias (both just missed at 50... the real number is probably around 70)
150 PA - K rate, line drive rate, pitches/PA
200 PA - BB rate, grounder rate, GB/FB ratio
250 PA - flyball rate
300 PA - HR rate, HR/FB
350 PA - sensitivity
400 PA - none
450 PA -none
500 PA - OBP, SLG, OPS, 1B rate, popup rate
550 PA - ISO
600 PA - none
650 PA - none
How can I do quick projections?
1. Take the last three years of data, and weigh it on a 5/4/3 scale.
2. Add a "2" that represents league average.
3. Average this out.
4. Adjust for park, league, age, etc.
Or just find the newest ZiPS or CHONE projections.
Is scouting still relevant?
Yes. It's another piece of information, just like numbers.
---
For mostly every other stat's definition and usage, I'd direct you to FanGraphs glossary and this.
Hopefully this is streamlined enough so that people who need primers and refreshers actually use it.
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You should add ERA to the list of worthless stats.
I miss George Steinbrenner. He was the man responsible for keeping the Yankees competitive.
In a large enough sample size it's not bad.
But we’re talking long careers, not 30 starts.
by R.J. Anderson on Jan 28, 2010 4:38 PM EST up reply actions
Maybe you should clarify what it can be used for then.
I miss George Steinbrenner. He was the man responsible for keeping the Yankees competitive.
I can't think of many purposes where people should use ERA on this site.
by R.J. Anderson on Jan 28, 2010 4:52 PM EST up reply actions
Given that the average sample size to draw definitive conclusions seems to be a season of data
Best to avoid ERA
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I still maintain ERA is a good description of past events.
In MLB is it a good illustration of true talent or good for prognasticating future performance? No.
Right, but who cares about past events in the minors
so much as the data which can tell us about our prospects abilities
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I do.
Have you seen a study on FIP in the minors? BABIP in the minors? Whether or not BABIP neutralizes and where? Until we get one, I’d rather go with a stat that is easier to neutralize to league and context.
No. And I'm going to go with FIP until some smart person runs those studies.
by R.J. Anderson on Jan 28, 2010 4:51 PM EST up reply actions
That's dumb.
Why limit information? It is definitely not unreasonable that certain minor league pitchers get hit harder than others.
If only we had stats like OPS and ISO against.
And scouting reports.
Oh well.
by R.J. Anderson on Jan 28, 2010 4:58 PM EST up reply actions
But MiLB CF are not ML CF.
Contrast Jennings in CF vs. Stanton. Or Jeff Dacker.
Huge disparity. Small influence on BABIP. Bigger influence on ISO, OPSA, ERA, etc.
Until someone does the study this is mostly for nothing.
by R.J. Anderson on Jan 28, 2010 5:03 PM EST up reply actions
Because it's true at the Major League level, and while it would be logical that it may differ at the minor league level, I'm not going to just assume it.
by R.J. Anderson on Jan 28, 2010 5:06 PM EST up reply actions
And minor league sample sizes are even smaller than MLB sample sizes.
Excuse me for not buying into that.
by R.J. Anderson on Jan 28, 2010 5:07 PM EST up reply actions
I said it was logical. I also said I'm not buying into it until it's proven.
There’s nothing more here for me to say.
by R.J. Anderson on Jan 28, 2010 5:11 PM EST up reply actions
I think you are right to a point
There are far more doubles in MILB than MLB largely to defense. The same can be said for triples. Nonetheless you can still get a feel across the same team.
Even in the majors there are major fielding discrepancies
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Given that HR are fielding independant
while there is a relationship between defense and ISO, on the balls in play its a difference of about .020 from best to worst
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Not as big, I'd argue.
Look at some of the positions guys played. Gamel at 3B, Dacker in CF, etc. etc. You don’t think all those extra free hits effects someone’s FIP by a large margin?
B/c innings last longer allowing for more BB K HR?
Then convert the outcomes to %’s instead of per 9
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That's a better idea.
I just don’t trust FIP anymore than ERA in MILB. That’s why I said “It’s also the best run-based stat to look at in the minors.” Should it be rellied on solely? No. No stats should for minor leaguers. I do think I’d rather have ERA for a prospect than FIP. It tells you a little more about their pitchability (I believe), easier to look at league/context wise, adjusts MORE for defense, etc.
I think it adjusts less
I was really big on FIP being inaccurate due to 9 innings, I looked at it in terms of %‘s and there wasn’t a big relationship based on defense. Maybe 0.10 in most extreme circumstances. It may be a bit more off in minors, but I trust that over scorekeeping judgements, higher incidence fo errors, and generally less range.
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I agree xFIP is useless
K,BB, and whiffs are about as good as it gets with a cynical eye on GB data as well. I feel comfortable averaging out the batted ball #s between MLS.com and statcorner
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I'm not sold on the BiP data, but i still think it's interesting.
I bet you could get more useful GB data from HR-rate and BABIP than GB rates.
Of all batted ball data
Ground ball is the most reliable, line drives/fly balls are far more subjective
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minorleaguesplits allows you the ability to neutralize for park and/or luck
Follow Me on Twitter @FreeZorilla
No, ERA is not worthless
ERA contains important aspects of pitching that FIP and tRA don’t, namely timing and BABIP skill. It’s just less reliable than FIP in a small sample size, because timing and BABIP are less in a pitchers’ control than K, BB, and HR (or FB) rates.
Over a large sample size, ERA is better than DIPS stats.
by vivaelpujols on Jan 28, 2010 7:36 PM EST up reply actions
No it's not
ERA is on a ridiculous scale
by Graham MacAree on Jan 29, 2010 11:13 AM EST up reply actions
The scale shouldn't make a difference in terms of value
Allowing a lot of errors or whatever isn’t a skill, it’s just random. Over a 5-6 seasons, RA is going to basically be ERA/.92 or something for most pitchers.
I agree with you that we should be moving towards a RA scale though.
by vivaelpujols on Jan 30, 2010 12:57 AM EST up reply actions
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