I have seen this stat often on this site and I understand what it is and its purpose but what I don't know that I want to know is how to calculate it. I would love to be able to calculate it myself and I'm sure other people on the site would as well.
I found this explanation on how to calculate it but the way it is explained is a little over my head as it looks like how you would do it on an Excel spread sheet and I do not know how to use excel. If anyone can explain to me how to do it that would be great.
0 recs | 65 comments
wOBA is a similar calculation to tRA
there’s no real shorthand way to calculate either, since they are both the summations of individual results over the course of a season.
seattlebruin - May 26, 2009
I understand that there is no shorthand way to do it but I'm willing to spend some time on it.
Kirk - May 26, 2009
wOBA (without SB/CS factor)
0.72*uBB + .75*HBP + .9*single + 1.24*double + 1.56*triple + 1.95*homerun + .92*rboe
Matthew - May 26, 2009
You forgot to divide by (plate appearances - IBB)
Graham MacAree - May 26, 2009
Yeah, that. I only listed the numerator.
Matthew - May 26, 2009
Out of curiosity, how would you factor SB/CS into wOBA?
Benne - May 26, 2009
I wouldn't, and don't.
If you wanted to however, you’d need to come up with weights in the same manner as done to come up with the weights for the above events.
Matthew - May 26, 2009
So wOBA treats all outs equally?
also, a little confused as to why your values differ from these linear weights
seattlebruin - May 26, 2009
Because you don't want 0.00 to be average
Graham MacAree - May 26, 2009
Gotcha
seattlebruin - May 26, 2009
Oh that seems to be very easy.
Thanks Matthew. I have just one question though, what is rboe?
Kirk - May 26, 2009
Reached base on error
Graham MacAree - May 26, 2009
Thank you.
Kirk - May 26, 2009
Which you can find on a player's Baseball-Reference splits page
Jeff Sullivan - May 26, 2009
Thank you guys for the help.
I am sure you have answered this question many times before and I’m glad you answered it once more.
Kirk - May 26, 2009
Why is reaching base on error worth more than a single?
Is it because you can get more than one base on an error?
Corco - May 26, 2009
Pretty much.
But there’s more to it. I’m going to have to let others explain it, though.
The Typical Idiot Fan - May 27, 2009
Reply fail.
Kirk - May 26, 2009
Is there an easy way to find a batter's RBOE?
Phil Hatzenbuehler - May 26, 2009
As Jeff said above, B-Ref has it
Graham MacAree - May 26, 2009
This is also a helpful link
http://www.insidethebook.com/woba.shtml
Jeff Sullivan - May 26, 2009
SB/CS
wOBA at FanGraphs includes stolen bases and caught stealing. The values for SB/CS in the formula are always pretty close to .5 and .25 respectively.
davidcameron - May 26, 2009
I assume you meant .25 and .5
Jeff Sullivan - May 26, 2009
Why is it that CS has a value?
I would think getting caught would have a negative value or none.
Kirk - May 26, 2009
Should be negative
A steal is about +0.25, while getting caught is about -0.50.
Jeff Sullivan - May 26, 2009
Has that changed?
I thought it was a 3 successful steal to 1 caught stealing ratio. Those numbers would make it a 2:1 ratio.
The Typical Idiot Fan - May 27, 2009
2:1 would be neutral
you have to successfully swipe the third before you’ve positively contributed to run scoring.
seattlebruin - May 27, 2009
Or this is a really rough estimate, I've always heard 70% is the number at which you're making a positive contribution
seattlebruin - May 27, 2009
They're approximations
After doing some research, the true values as derived by Tango are closer to +0.2 and -0.47.
Jeff Sullivan - May 27, 2009
I have another StatCorner related question:
Why is Zack Greinke’s tRA+ 175, while his tRA is 1.29 and the league average is 5.06? 1.29/5.06 is 3.92, so why doesn’t he have a 392 tRA? Or am I way off base about how ERA is calculated?
Decatur - May 27, 2009
*a 392 tRA+ I mean
Decatur - May 27, 2009
From the Glossary
Jeff Sullivan - May 27, 2009
Damn, I should've just looked there.
Thanks for answering my question in any case, Jeff.
Decatur - May 27, 2009
This might better be suited for the statistical analysis thread
but how do you convert tRA into runs?
vivaelpujols - May 27, 2009
I mean
if you apply the coefficients on Graham’s primer to batted ball rates of players, how do you convert those to tRA?
vivaelpujols - May 27, 2009
How far back have you gone in your tRA reading?
I’m pretty sure he explained this in a huge post sometime a while ago.
Jeff Sullivan - May 27, 2009
I read the tRA primer, but I couldn't find anything else on it on LL (besides the "no numbers" version)
It says the formula is tRA = expected_runs/expected_outs*27. I tried doing that and I got a “bad” number. Maybe I’m calculating xRuns and xOuts wrong. Is it just the out or run coefficients for each outcome, multiplied by the frequency, and then added all together?
vivaelpujols - May 27, 2009
"Is it just the out or run coefficients for each outcome, multiplied by the frequency, and then added all together?"
Yes. If you’ll allow me a bit of a messy comment:
Call the overall total, expected runs, and expected outs of outcome [y], i_[y], r_[y] and o_[y] respectively.
xR is therefore i_[j]r_[j] summed over j=K, BB, HBP, etc (i.e. the tRA outcomes)
xO is therefore i_[j]o_[j] summed as above
tRA is then (xR/xO)*27
Graham MacAree - May 27, 2009
oh fucking SBN
Graham MacAree - May 27, 2009
Insert * as appropriate
Graham MacAree - May 27, 2009
gotcha
thanks
vivaelpujols - May 27, 2009
Can't you just weigh slugging and OBP to get a rough, non-steal wOBA?
vivaelpujols - May 27, 2009
Given that wOBA is readily available and updated daily, I don't see the point
Jeff Sullivan - May 27, 2009
That's called GPA and THT has it. It's 1.8*OBP + SLG
But as Jeff says, why not use the better metric?
Matthew - May 27, 2009
For reference, the comments of:
This.
CapSea - May 27, 2009
GPA is a decent, off the top of your head, way to see which of two players is a better hitter
Obviously, you’d use wOBA whenever you have the chance, but if you just want a quick and dirty way to estimate players talent, you could use GPA.
vivaelpujols - May 27, 2009
When is calculating GPA going to be easier than checking wOBA?
Aaron Campeau - May 27, 2009
/shrugs
vivaelpujols - May 27, 2009
You are trapped on a desert island with the OBP and Slugging of every baseball player in a book?
joof - May 28, 2009
When you're at a baseball stadium
seattlebruin - May 28, 2009
Not many scoreboards list OBP and SLG
Jeff Sullivan - May 28, 2009
Ours does now
Graham MacAree - May 28, 2009
We made them!
Robert - May 28, 2009
Angel Stadium does
seattlebruin - May 28, 2009
Buy a smartphone luddite.
Aaron Campeau - May 28, 2009
I have a Dare
it doesn’t like StatCorner
seattlebruin - May 28, 2009
If someone gives me $20K
I’ll develop a mobile version of the site.
Matthew - May 28, 2009
Works well enough on my phone.
Aaron Campeau - May 28, 2009
Fangraphs will do in a pinch.
Aaron Campeau - May 28, 2009
Wait since when does FanGraphs show wOBA?
seattlebruin - May 28, 2009
Also, FanGraphs won't let me search for players on my phone
seattlebruin - May 28, 2009
That's odd.
Aaron Campeau - May 28, 2009
Since last November.
marc w - May 28, 2009
They've had it for a while.
SC wOBA is better but Fangraphs wOBA is close enough for the situation you’ve described.
Aaron Campeau - May 28, 2009
Still doesn't solve that the stupid Dare's browser gives me an error whenever I try to search for a player
says I’ve reached the character limit as soon as I type the first letter.
seattlebruin - May 28, 2009
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