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Thursday, March 28, 2013

FanGraphs: Cameron: Unifying Replacement Level

What is it good…AAARGGH!...the follow-up.

After reading Caple’s article, David Appelman and I began discussing the idea of reaching out to Sean Forman and seeing if he was interested in agreeing to a unified replacement level. Before we could actually even send that email, Sean reached out to us with the exact same idea. And so, today, we’re pleased to announce that Baseball-Reference and FanGraphs have adopted that unified replacement level, allowing our two models to now measure players on the same scale.

As David noted a few minutes ago, this new unified replacement level is now set at 1,000 WAR per 2,430 Major League games, which is the number of wins available in a 162 game season played by 30 teams. Or, an easier way to put it is that our new replacement level is now equal to a .294 winning percentage, which works out to 47.7 wins over a full season. Conveniently, this number is almost exactly halfway in between our previous replacement level (.265) and Baseball-Reference’s previous replacement level (.320), though the number wasn’t chosen solely as an equal compromise.

...The higher baseline brings our scale down slightly, but we think that change is worth making, as a unified replacement level will allow for comparisons of our apples versus their apples, and will eliminate needless confusion based around an area that didn’t need to cause confusion. These changes weren’t made lightly, and we know that there is always some resistance to any sort of change, but we hope that you see the unification of replacement level between the two sites as a positive overall.

While there will never be one single agreed upon WAR calculation — I’d call that a feature and not a bug, but that’s another post — the common baseline will give us a better opportunity to explore where the real differences are, rather than being tricked into seeing big gaps where none actually exist.

So, that’s the short version of the story behind this change. We’ll have more on this going forward, including a post coming later this afternoon on why we need replacement level to begin with, but for now, we hope you guys see this as a step forward for WAR as a metric.

Repoz Posted: March 28, 2013 at 02:41 PM | 27 comment(s) Login to Bookmark
  Tags: sabermetrics

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   1. Edmundo got dem ol' Kozma blues again mama Posted: March 28, 2013 at 03:06 PM (#4398618)
"Stop the War" was no "Agent Double-O Soul"
   2. 'zop sympathizes with the wrong ####### people Posted: March 28, 2013 at 03:06 PM (#4398619)
#6 replacement level?
   3. SG Posted: March 28, 2013 at 03:13 PM (#4398622)
I think in its prime the new replacement level could hit .265/.294/.320 while playing awful defense.
   4. 'zop sympathizes with the wrong ####### people Posted: March 28, 2013 at 03:18 PM (#4398624)
Yippee.
   5. Mefisto Posted: March 28, 2013 at 03:27 PM (#4398631)
When will this be reflected on the sites?
   6. SG Posted: March 28, 2013 at 03:47 PM (#4398645)
When will this be reflected on the sites?


They are already reflected on Fangraphs. Not sure when BB Ref will be updated.
   7. bunyon Posted: March 28, 2013 at 03:54 PM (#4398649)
It's spring. Replacement level is in the best shape of its life.
   8. Slivers of Maranville descends into chaos (SdeB) Posted: March 28, 2013 at 03:58 PM (#4398652)
Don't they need to come to an agreement on the filioque first?
   9. cardsfanboy Posted: March 28, 2013 at 04:06 PM (#4398656)
When will this be reflected on the sites?


They are already reflected on Fangraphs. Not sure when BB Ref will be updated.


That was my first question also. Unfortunately I don't remember anyone's war(by heart) from before yesterday so I probably couldn't tell if there was a change by just looking.

Now if we could just apply the rule of 17 to relief pitcher before establishing their war, and ultimately figure out a way to chain reliever war(that last one is probably never going to happen)
   10. SG Posted: March 28, 2013 at 04:13 PM (#4398658)
Now if we could just apply the rule of 17 to relief pitcher before establishing their war


If you are comparing relievers to relievers why would you need to do this?
   11. Dan Posted: March 28, 2013 at 04:49 PM (#4398679)
How does this unified replacement level compare to the replacement level that Prospectus uses for calculating WARP and VORP?
   12. snapper (history's 42nd greatest monster) Posted: March 28, 2013 at 04:53 PM (#4398682)
If you are comparing relievers to relievers why would you need to do this?

Doesn't the use of LI make comparison of RPs impossible?

An RP who puts up a 150 ERA+ with an LI of 1.0 was just as good as a closer who did the same with an LI of 2.0. It's purely a manager's decision that is giving the closer higher WAR.
   13. AROM Posted: March 28, 2013 at 04:57 PM (#4398683)
How does this unified replacement level compare to the replacement level that Prospectus uses for calculating WARP and VORP?


Not sure if Colin is going to make changes, but he has been involved in the treaty talks.
   14. Dan Posted: March 28, 2013 at 05:14 PM (#4398696)
An RP who puts up a 150 ERA+ with an LI of 1.0 was just as good as a closer who did the same with an LI of 2.0. It's purely a manager's decision that is giving the closer higher WAR.


But managers' usage decisions affect all players' WARs. A starting pitcher with 4 WAR in 28 starts is the same performance level as a guy with 3 WAR in 21 starts. For relievers playing time AND situation dictate value, but it's just adding another level of manager decisions to their value. It's impossible to separate any player's value from the manager's decisions on how to use him.

If you want to compare it to a position player, presumably Miguel Cabrera is more valuable playing a decent 3B than he'd be as a statue at SS. Even the choice to play him at 3B instead of 1B last year affected his value.
   15. Walt Davis Posted: March 28, 2013 at 05:21 PM (#4398701)
Hallelujah!

But, but, but ... couldn't we have just gone with 48 wins?

So an average player in b-WAR terms is now, what, about 2.5 WAR
   16. cardsfanboy Posted: March 28, 2013 at 05:41 PM (#4398709)
If you are comparing relievers to relievers why would you need to do this?


Mostly because the adjustments aren't enough(assuming I'm reading the methodology correctly, .1125 runs per game doesn't seem to match the nearly .40 ERA difference between relievers and starters.) Of course anything that would reduce the ridiculously high war numbers for relievers would be a great thing.
   17. Sean Forman Posted: March 28, 2013 at 07:16 PM (#4398757)
Posted this on FG:
Just to follow up Dave's post. Glad we could come together on this.

I should have B-R up to date tomorrow morning. Lots of things that have get rebuilt, so that will happen tonight and I'll push it live tomorrow.

The numbers will still be different (especially on the pitching side), but we will both be alotting WAR out of the same sized bucket now. I've done some eyeball comparisons and on the hitting side, the career totals for our 1-N career leaders are very close.

On the batting side,
B-R's #100 has 63 WAR and FG's #100 has 62.6.

on the pitching side
B-R's #100 has 50 WAR and FG's #100 has 47.6.

I'll tweet and post on the b-r blog when b-r is updated.
   18. McCoy Posted: March 28, 2013 at 08:04 PM (#4398783)
Oddly enough Darwin Barney has lost WAR. He was at 4.6 this morning and now he is at 4.16.

   19. valuearbitrageur Posted: March 28, 2013 at 08:52 PM (#4398806)
Oddly enough Darwin Barney has lost WAR. He was at 4.6 this morning and now he is at 4.16.


Write it up as yet another Theo Epstein missed trade opportunity.
   20. Moeball Posted: March 29, 2013 at 01:16 AM (#4398937)
Some have called me a liberal nancy-boy because I prefer WAA to WAR.
   21. Sean Forman Posted: March 29, 2013 at 08:35 AM (#4398976)
Moeball, for single seasons I think WAA is just fine for picking the MVP etc. It's really the same number when comparing players with similar playing time. I think it falls down a bit when looking long term or multiple years.

We've pushed the new WAR totals to the site, so you should be seeing slightly higher numbers than previously.
   22. Swedish Chef Posted: March 29, 2013 at 09:05 AM (#4398985)
I think it falls down a bit when looking long term or multiple years.

I like for HoF purposes, because I don't think churning out average seasons should add to the HoF-case.
   23. AROM Posted: March 29, 2013 at 09:28 AM (#4398997)
To further add to his legend, Mike Trout added another 0.2 WAR in the offseason. Sadly, it was not enough to retroactively push the 2012 Angels into the postseason.
   24. Darren Posted: March 29, 2013 at 09:46 AM (#4399015)
Great news. Very nice to see. Thanks Sean and Davids.
   25. RMc is a fine piece of cheese Posted: March 29, 2013 at 09:46 AM (#4399016)
Now that the B-R/Fan Graphs Treaty has been signed, when does the Baseball-Ref Civil War (Treaty vs Anti-Treaty) start?
   26. Walt Davis Posted: March 29, 2013 at 06:13 PM (#4399356)
Moeball, for single seasons I think WAA is just fine for picking the MVP etc. It's really the same number when comparing players with similar playing time. I think it falls down a bit when looking long term or multiple years.

Disagree. It's most useful for long term or multiple years. As you note, for equal playing time, WAR and WAA give you the same information. So the only purpose of WAA is to compare across unequal playing time and it makes almost no sense to make single-season comparisons of players with substantially unequal playing time.

WAA vs WAR only becomes useful when comparing across multiple years but different levels of playing time. For HoF purposes, it's a quick and dirty way to get at prime vs. career. Walker produced 48 (new) WAA in 8000 PA; Winfield produced 24 WAA in 12000 PA (or using ARom's "rule", 29 WAA in 9500 PA ... man did Winfield hang on). Walker has a 8 WAR advantage but a 24 WAA advantage.
   27. Moeball Posted: March 31, 2013 at 05:18 PM (#4400276)
WAA vs WAR only becomes useful when comparing across multiple years but different levels of playing time. For HoF purposes, it's a quick and dirty way to get at prime vs. career.


Walt, I think a good example of that shows up, for example, when looking at all-time rankings of 2B. I noticed that Hornsby is just barely ahead of Collins for career WAR (127 to 124). But when you look at WAA, it's Hornsby by a wide margin (97 to 79). It really tells you just how high a player's peak really was.

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