+/-, RZR, and New Fielding Stats

There have been a few changes to the fielding sections of the site.

The biggest change is that John Dewan’s Fielding Bible +/- runs saved is now available on all the player pages and leaderboards going back to 2003. The stats that are associated with +/- runs saved are:

All in Runs Above Average:
rSB – Stolen Base Runs Saved (Catchers/Pitchers)
rBU – Bunt Runs Saved (1B/3B)
rGDP – Double Play Runs Saved (2B/SS)
rARM – Outfield Arms Runs Saved
rHR – HR Saving Catch Runs Saved
rPM – Plus Minus Runs Saved
DRS – Total Defensive Runs Saved

We’ve also added Revised Zone Ratings, which The Hardball Times used to carry. I’ll quote from THT:

Revised Zone Rating is the proportion of balls hit into a fielder’s zone that he successfully converted into an out. Zone Rating was invented by John Dewan when he was CEO of Stats Inc. John is now the owner of Baseball Info Solutions, where he has revised the original Zone Rating calculation so that it now lists balls handled out of the zone (OOZ) separately (and doesn’t include them in the ZR calculation) and doesn’t give players extra credit for double plays (Stats had already made that change). We believe both changes improve Zone Ratings substantially. To get a full picture of a player’s range, you should evaluate both his Revised Zone Rating and his plays made out of zone (OOZ). You can read more about the Revised Zone Ratings in this article.

BIZ – Balls in Zone
Plays Made – Total Plays Made
OOZ – Plays Made out of Zone

Then there’s some other fielding stats that were added such as:

FE – Fielding Errors
TE – Throwing Errors
DPS – Double Plays Started
DPT – Double Plays Turned
DPF – Double Plays Finished
Scp – First Baseman Scoops

Everything is available in the player pages and leaderboards and will be updated nightly.

This season’s UZR updates will be coming soon and we’ll have more on that later.



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David Appelman is the creator of FanGraphs.


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Double06
Member
Double06
6 years 2 months ago

I’m floored, Dave. Thank you, thank you, thank you.

Jack Moore
Member
Member
6 years 2 months ago

Blengino got to you, huh?

Larry Smith Jr.
Guest
6 years 2 months ago

This is completely outstanding. Awesome. Thanks Dave, this site is the best!

supermets
Guest
supermets
6 years 2 months ago

Great!

My question: Is there any reason to use RZR when UZR is available?

steagles
Guest
steagles
6 years 2 months ago

RZR has a defined, tangible output. it tells you the rate of plays made to plays in the zone. you combine that with plays made out of zone (OOZ), and fielding %, and you’ve got a hell of a lot more information that UZR could convey.

vivaelpujols
Guest
6 years 2 months ago

Right. RZR isn’t really a great measure of value, but it is more descriptive and intuitive than UZR. It’s a great gateway fielding stat.

Nny
Guest
6 years 2 months ago

I don’t know if it’s ever been addressed, but when Dewan released his Fielding Bible Volume 2, his outfield arm ratings were messed up.

Due to what the stats are trying to convey, if you add up all the defensive stats for a position in a league, you get zero (or extremely close to it).

This is not the case with the arm ratings. You get something like +150 at RF, +100 at CF, +50 at LF (I don’t remember the exact numbers, I had added them up when the book came out a year ago).

Meaning that total plus/minus for OFers were incorrect because the arm runs weren’t runs above average. I mean, comparing two players was fine, i.e. if OFer A is five runs better than OFer B, it’s going to show that. But the +10 OFer wasn’t 10 runs above average, he was less than that.

philkid3
Member
6 years 2 months ago

Just yesterday I was thinking of renewing my Bill James Online account.

Kevin S.
Member
Kevin S.
6 years 2 months ago

What’s RZR scaled to? +/-, like UZR, is intuitive: positive good, negative bad. Not sure how we’re supposed to evaluate RZR.

J.T.
Guest
6 years 2 months ago

Kevin,

RZR is simply the rate of balls in a player’s zone converted into outs. You can change this into plays and runs above/below average by comparing the player’s RZR to the league average. UZR is a rate, but it is presented as runs saved or cost compared to the average player at the position.

Let’s say, for example, we have a league average RZR at SS of .800. The player we’re looking at has 440 balls hit into his zone, and he converts .810 of them into an out. This means he’s made 356 plays. A league average SS, however, is expected to make .800*440 = 352 plays, meaning that our player has made 356 – 352 = 4 plays above an average shortstop. Converted to runs, that’s about +3 runs saved.

This isn’t taking into account a player’s Out Of Zone (OOZ) plays, which can be done by looking at the player’s OOZ rate compared to balls hit in his zone.

I hope that helps some.

Kevin S.
Member
Kevin S.
6 years 2 months ago

It does, and I actually misstated my question – it wasn’t the scaling I was having issues with, it was knowing the baseline used. Thanks.

J.T.
Guest
6 years 2 months ago

Dave, thank you so much for bringing these new stats to the site!

One question, though- is it possible to also present scoop opportunities for first basemen as well? Otherwise, we’ve got no real context.

firnie14
Member
6 years 2 months ago

It’s awesome to see sabermetrics continue to grow like this

mickeyg13
Member
6 years 2 months ago

Thanks, this is great!

I do want to point out though that there seems to be a problem on the leaderboards. If I look at 2009 outfielders I see that Nyjer Morgan appears near the top at +22. If I look at 2009 for all players then Morgan is nowhere to be found when he should be near the top. Might this glitch be related to the fact that he played for two teams last year?

mickeyg13
Member
6 years 2 months ago

OK I’m confused…what is the difference between rPM and +/-? I thought that +/- was scaled to plays, not runs?

Joe
Guest
Joe
6 years 2 months ago

Do park factors come into play at all with rARM? ( I guess you could look at home/road splits but I’m guessing the sample sizes are probably already pretty small?)

For example LF in Boston seems like a huge advantage for preventing an extra base (either 2nd to home 1B to 3B or even 1B to home on on a double). And on the opposite end a large park may hurt (where it may be easier to score from 1st on a double)? Or say Coors where you may be playing deep and it might be easier to take an extra base on a single.

SF 55 for life
Member
SF 55 for life
6 years 2 months ago

How long before +/- sample become reliable? 2 years or 3?

mickeyg13
Member
6 years 2 months ago

As with all the stats, there is not a single point where they switch from “unreliable” to “reliable.” Larger sample sizes mean they will be more reliable, and the larger the better.

There is, however, a point where there is more signal than noise in the data. In other words, once we have n datapoints we think a player’s true value is closer to his observed value than to the mean value. Is that what you are after? If so I would guess it’s pretty much the same as UZR…

J.T.
Guest
6 years 2 months ago

2-3 years of defensive data is roughly equal to one year of offensive data. It depends on the position, though.

Gina
Guest
Gina
6 years 2 months ago

Are UZR and +/- on the same scale?

J.T.
Guest
6 years 2 months ago

Yes; they’re both presented as runs above or below the average fielder at the position.

Kirkwood
Member
Kirkwood
6 years 2 months ago

This is great.

RKO36
Guest
6 years 2 months ago

All hail David Appelman.

Josh Fisher
Guest
6 years 2 months ago

Thinking about using this stuff for a THT article Tuesday…how is this data gathered? By BIS? And are certain ballparks not covered, or covered differently? Only 20 players have Scoops to their name from last season.

Colin Wyers
Guest
6 years 2 months ago

Scoops should be first base only.

Both DRS and UZR should be based off the exact same play-by-play and batted ball data, collected by BIS.

Judy
Member
Judy
6 years 2 months ago

Switch from qualified only to all players, there are more than 20.

TJ
Guest
TJ
6 years 2 months ago

YAY!!!!!

Jon
Guest
Jon
6 years 2 months ago

So just to be clear, UZR should be compared to DRS, not rPM, right?

Colin Wyers
Guest
6 years 2 months ago

Essentially. The equivalent for rPM should be ErrR+RangeR.

philkid3
Member
6 years 2 months ago

Well put, Colin!

pft
Guest
pft
6 years 2 months ago

This is great.

So WAR is still based on UZR Defensive runs saved?. There is quite a difference between +/- DRS and UZR Defensive runs saved for some players (example +4 for JD in +/- and + 10.5 by UZR). Any chance of averaging the 2 to smooth things out and improving overall accuracy (in meterology several models are averaged to improve accuracy in forecasts).

philkid3
Member
6 years 2 months ago

For people with questions on the different components, here’s an explanation from the website:

Defensive Runs Saved (Runs Saved, for short) is the innovative metric introduced by John Dewan in The Fielding Bible—Volume II. The Runs Saved value indicates how many runs a player saved or hurt his team in the field compared to the average player at his position. A player near zero Runs Saved is about average; a positive number of runs saved indicates above-average defense, below-average fielders post negative Runs Saved totals. There are eight components of Runs Saved:

• Plus Minus Runs Saved evaluates the fielder’s range and ability to convert a batted ball to an out.
• Earned Runs Saved measures a catcher’s influence on his pitching staff.
• Stolen Base Runs Saved gives the catcher credit for throwing out runners and preventing them from attempting steals in the first place.
• Stolen Base Runs Saved measures the pitcher’s contributions to controlling the running game. • Bunt Runs Saved evaluates a fielder’s handling of bunted balls in play.
• Double Play Runs Saved credits infielders for turning double plays as opposed to getting one out on the play.
• Outfield Arm Runs Saved evaluates an outfielder’s throwing arm based on how often runner advance on base hits and are thrown out trying to take extra bases.
• Home Run Saving Catch Runs credits the outfielder 1.6 runs per robbed home run.

Tigerdog
Guest
Tigerdog
6 years 2 months ago

Glad to see the RZR numbers posted on fangraphs, Thank You!
Question- Is the “runs saved” statistic an actual number, or a projection based on other stats?
2. As a classic example, Placido Polanco led the majors in UZR among second basemen in 2009, yet he was way down the list even among AL second basemen in RZR. Which is a better measure of Polly’s fielding performance vs his peers?
And here’s the modest position from whence I come: I like RZR. Number of balls hit into a player’s “zone” that he turns into outs. Okay, I can see that it has to be taken together with OOZ plays. But UZR confuses me. The explanation of those numbers make my head spin, and that’s extremely rare for me. Any clarification using PP as an example would be appreciated.
Tigerdog

3FingersBrown
Guest
6 years 2 months ago

Fantastic stuff. Keep up the great work!

razor
Guest
razor
6 years 2 months ago

This is awesome and I’m one who actually likes the RZR/OOZ component that Hardball Times used to show. Plus/Minus and UZR may be the industry standard now, but I still like to see if RZR/OOZ provide support.

Thanks for adding this at FanGraphs. This really is awesome.

obsessivegiantscompulsive
Guest
6 years 2 months ago

Thank you! You take a great site and continually make it better, it is much appreciated – as you can see by the long line of comments, and I’m happy to add my kudos.

nick
Guest
nick
6 years 2 months ago

Awesome! Thank you.

CJ
Guest
CJ
6 years 2 months ago

I agree with the sentiment above…this is excellent. I also like to look at OOZ, because I think it tells you a different piece of information about players. I think Hardball Times originally separated RZR and OOZ because out of zone plays should have more value, and HT decided to let the user assign their own weighting to OOZ. I think it’s interesting to see the different profiles for players who have high RZR ranking but low OOZ, and vice versa, for example. I also like comparing Fielding Bible and UZR results to get a higher comfort level in the defensive ratings.

I subscribe to Bill James on-line part because I like the defensive data; and I will continue subscribing in the future. I don’t want to punish that web site when they do a good thing like sharing defensive data with Fangraphs. (Besides, Bill James on-line is cheap.)

Jim Don Seculius Dudek
Guest
Jim Don Seculius Dudek
6 years 2 months ago

I am new to FanGraphs. I have seen the Fielding Bible book in stores and perused it. I am trying to get into this but feel I need a beginner’s course in sabermetrics.

Rob
Guest
Rob
6 years 2 months ago

I feel stupid asking this….but is the “+/-” the same as DPS?

Because if you compare DPS to +/- on THT website, they’re off. In 2008, Robinson Cano posted a DPS of -13 but a +/- of -16. Every player I look at is the same. Chase Utley has a DPS of 33, but a +/- of 47.

What’s the cause of this difference?

Rob
Guest
Rob
6 years 2 months ago

Oops. That was my mistake. I meant the Fielding Bible site. http://www.fieldingbible.com/

Since the +/- is different from DPS, is there comprehensive +/- data available other than the Fielding Bible site? I see a lot of new fielding info here on Fangraphs, but I’m not seeing the +/-.

I mean, is this something really simple that I’m overlooking, or am I just really confused (or possibly both)?

J.T.
Guest
6 years 2 months ago

Rob,

Plus/Minus is the same system as DRS. The difference between the two is that Plus/Minus is presented in plays above or below average; DRS is presented as *runs* above or below average.

pft
Guest
pft
6 years 1 month ago

Looking at DRS at the team level just now, I notice that teams collectively are + 232 runs above average. How is this possible, should it not come out to 0?. If it should then this inflation comes out to about 7 runs per team and must also be inflated at the player level.

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