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THE BOOK--Playing The Percentages In Baseball

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Wednesday, February 06, 2008

How to calculate WAR

By Tangotiger, 11:10 AM

WAR is wins above replacement.  Replacement is defined very specifically for my purposes: it’s the talent level for which you would pay the minimum salary on the open market, or for which you can obtain at minimal cost in a trade.

For nonpitchers, that level is set at -2.25 wins per 162 games, below the average for that league.  Since the same stats of an average AL player is better than the same stats of an average NL player (i.e., the AL is the better league), we have different replacement levels.  Those levels are -2.5 wins per 162 games in the AL, and -2.0 wins in the NL.

The positional adjustments are:
+1.0 wins C
+0.5 SS/CF
+0.0 2B/3B
-0.5 LF/RF/PH
-1.0 1B
-1.5 DH

These are needed so that an average fielding 1B is not valued the same as an average fielding SS.  The DH and PH should be at -2.0 wins (that is, a poor fielding 1B and a DH have the same fielding+positional value).  However, as per The Book, it’s harder to DH, so we give them a 0.5 win boost.  The PH gets an extra 1 win boost over the DH, because PHing is much harder.

For pitchers, that level is set at .380 win% for starters and .470 for relievers.  The exact same pitcher will perform much better in a relief role than in a starter role.  So, you need different baselines.  You can read the relevant chapter in The Book for that.  As with nonpitchers, you need different baselines in each league: .370, .460 in the AL, and .390, .480 in the NL.

For closers, there is a closer replacement level of .570 win%.  Any wins above this level gets multiplied by his Leverage Index (LI).  That is, while he is not responsible for the LI he finds himself in, he is responsible for his talent that allows him to take advantage of the extra leverage (sort of like Ozzie Smith gets to play SS and reaps the benefit of all the extra opps).  We are only giving credit to the closer for the leverage above the .570 win% level.  Credit GuyM for this insight.



This section below is not required to understand the above.  It is presented here for the hardcore among you.


To convert wOBA for a hitter into wins: (wOBA - .338) / 1.15 * 700 / 10.5 will give you wins above average.  (The .338 is whatever the league average wOBA is, which is EXACTLY equal to whatever the league average OBP is; 1.15 is the relationship between wOBA and runs; 700 is the number of PA per 162 games; 10.5 is the relationship between runs and wins.) Adding in the wins above average at the position plus the positional adjustment gives you wins above average per 162 games.  Add in the replacement level, and that gives you WAR per 162 games.  Simply multiply that number by the percentage playing time you expect (no more than 90%, typically at 85% for regulars), and you have your WAR.

For starters, you multiply the wins above replacement by the number of full games (expected innings divided by 9).  Use 20-24 for your full-time starters.  Use 7-9 full games for your relievers.


Ok, so how many wins above replacement are there in AL and NL?

For nonpitchers in AL:
2.5 * 8 * 14
+ 1.0 * 1 * 14
+ 2.0 * 0.1 * 14
= 297 wins. 
That’s 2.5 wins for every average AL nonpitcher at the 8 fielding positions, times 8 AL nonpitchers times 14 teams.  The second line is the average hitter as a DH.  The third line is the average hitter as a PH.

For starters in AL:
(.490-.370) * .66 * 162 * 14 = 180 wins
That’s a .490 win% for the average starter, times 66% of the innings per game, times 162 games times 14 teams.

For relievers in AL:
(.520-.460) * .34 * 162 * 14 = 46 wins

For closers bonus in AL:
(.610-.570) * 1.8 * 8 * 14 = 8 wins
The 8 is the number of full games (72 innings) we give a closer.  The 1.8 is his LI.

Adding it up, and we get 531 replacement wins in the AL. Nonpitchers get 56% of that and pitchers get 44%.  Of pitchers, starters get 77% and relievers 23%.

Repeating for the NL.

For nonpitchers in NL:
2.0 * 8 * 16
+ 0.5 * 0.05 * 16 (DH)
+ 1.5 * 0.40 * 16 (PH)
= 266 wins. 

For starters in NL:
(.490-.390) * .64 * 162 * 16 = 166 wins

For relievers in NL:
(.520-.480) * .36 * 162 * 16 = 37 wins

For closers bonus in NL:
(.610-.570) * 1.8 * 8 * 16 = 9 wins

Adding it up, and we get 478 replacement wins in the NL. Nonpitchers get 56% of that and pitchers get 44%.  Of pitchers, starters get 78% and relievers 22%.



As you can see, despite having 2 more teams, there is more talent in the AL, on the order of +53 wins.  This was of course manipulated by me with the replacement levels.  This would imply about $120MM more payroll (above the minimum) in the AL than the NL.  And that’s close to reality.

The total number of replacement wins is 531 in the AL and 478 in the NL for 1009 wins (average of +33.6 wins above replacement; since the average team wins 81, that sets the replacement team at 47.4 wins, or 0.292 win%).

The average AL team is 531/14= +38 wins above replacement (or +.234 wins above replacement per game), while the average NL team is 478/16= +30 wins (or +.184 wins above replacement).  Since the replacement level is .292, that gives us the following as the average win levels in each league:
AL: .292 + .234 = .526
NL: .292 + .184 = .476

A head-to-head of a .526 team facing a .476 team would result in a win% of .550 for AL.  That’s also the reality of the situation, and the replacement levels for the two leagues was set with this in mind.



The totals by position:
563 wins nonpitchers
346 wins starters
100 wins relievers
1009 wins total

This implies that 56% of your payroll (above the $400K minimum per player) should go to nonpitchers, 34% to starters, and 10% to relievers.  For reasons of risk, you might give a bit less to your pitchers.

#1    Tangotiger 2008/02/06 @ 11:34 AM

If you accept the above, you can see why Win Shares severely undervalues starting pitchers.  Using Studes’ Win Shares database, since 2002 34% of all win shares goes to pitchers (starters and relievers).  Of those, IIRC, it’s split pretty much two-thirds one-third between SP/RP, meaning 11% for RP and 23% for SP.

To recap, I give 56% of the wins to nonpitchers, while Win Shares gives 66%.  I give 34% to SP, while Win Shares gives 23%.  We agree on relievers.


#2    Bobby Swift 2008/02/06 @ 12:10 PM

Thanks for this - I’ve been trying to piece together the methodology from many different posts, it’s great to have it all in one place.

Could you describe how you translate fielding runs into wins, and which defensive metrics you feel most confident in?


#3    Tangotiger 2008/02/06 @ 12:30 PM

10.5 runs per win.

I use the Fans Scouting Report, UZR, and Dewan’s Plus/Minus.  In terms of weighting, it’s probably 40/35/25.


#4    Rally 2008/02/06 @ 01:14 PM

Is Dewan’s +- available anywhere for more than just the leaders and trailers?


#5    Tangotiger 2008/02/06 @ 01:43 PM

By compiling for Dewan (of names on his ballot) the top 10 for each position from the Fans’ Scouting Report, I get two things: the James Handbook, and the not-for-redistribution Fielding Bible (as of mid-September).


#6    Jared 2008/02/06 @ 03:44 PM

I’m definitely bookmarking this. Thanks for posting this resource.

Could you show the exact formula you use to determine Win Percentage for pitchers? Take Tom Glavine, for example, who’s projected to post a 4.50 ERA and pitch 180 innings. Thanks.


#7    Tangotiger 2008/02/06 @ 04:05 PM

Figure out the league average ERA, which in this case is 4.40.

Add up the two numbers to get your run environment: 8.90 earned runs per 9IP.  Divide by .92 to get that into total runs (including unearned).  That’s 9.67.

Use PythagenPat to get the exponent: 9.67^.28=1.89

W/L = (4.40/4.50)^1.89 = .958
W/(W+L) = .958/(.958+1) = .489

So, Tom Glavine would have a win% of .489.


#8    Jared 2008/02/06 @ 04:21 PM

Alright, I think I got it now. Thanks.


#9    david smyth 2008/02/06 @ 04:30 PM

A comment on the positional values--specifically the -.5 for LF/RF and the -1.0 for 1B. Those were determined from your studies on players switching positions, right?

But here’s something I’ve been wondering about. Here are the approximate number of players who played at each position in 2007:
C, 120
SS, 130
2B, 140
CF, 160
3B, 165
1B, 175
RF, 210
LF, 245

It reflects the traditional def. spectrum almost perfectly, except for 1B. Why is that? The players who switch positions are a special subset of all players, because they already have the basic skills to play at each positions. But, if you consider all players, and asked them to play all positions ‘cold’, maybe they would do better in LF/RF than at 1B, because of the specialized skills needed at 1B, and the number of plays he is involved in. Maybe the ‘lag’ time of adapting to each new position should be given more weight in the def. spectrum determination.


#10    Tangotiger 2008/02/06 @ 04:49 PM

That’s an interesting list.  Since a LF and RF are virtually identical, what would your count produce if you simply said “corner OF”?  If it’s more than 350 (double the 175 of 1B), I think you’ve got something.


#11    david smyth 2008/02/06 @ 06:42 PM

I guess I could look at the source and figure that out by hand, but I’m not sure that the similarity in the skills needed to play LF and RF should be a way to mitigate or invalidate the idea I am suggesting. I mean, there are also similarities between 1B and 3B, and between SS and 2B. If LF and RF require almost identical skills, and that means that there are more players a team can/does choose from to put at those positions, that simply confirms that 1B is more unique. If you came at this knowing nothing about how each position does on offense, and the data I gave above, you might very well conclude that 1B is more ‘difficult’ than LF or RF for MLB players.


#12    tangotiger 2008/02/06 @ 07:43 PM

Sure, there are similarities among any pair, but by far the strongest is between LF and RF.  The amount of shared games at those positions tells you that too.

And the reason you have more players at those positions, is that they are 2 positions, not 1.  I just don’t see how counting Endy Chavez as a RF and as a LF tells you anything other than he played a corner OF.


#13    Josh 2008/02/06 @ 08:00 PM

Historically, does the .5 win gap between CF and 2B/3B hold? Going back more than twenty years, it seems that the skill sets required for each position, but especially 2B, have changed. Is this an accurate perception?


#14    david smyth 2008/02/06 @ 09:19 PM

The problem with your line of analysis, Tango (IMO), is that a team needs to have a separate fielder at each position at any point in time. So, the position ‘utility’ advantage that a RF may be credited with (because he could also play LF), has to be balanced against the uniqueness of the skills needed to play 1B, (at a moment’s notice,which may be the main point in my analysis).


#15    tangotiger 2008/02/06 @ 10:08 PM

I’m not sure how much uniqueness is required for 1B.  I remember when Galaragga (or was it Floyd) went down, Larry Walker stepped right in, no problem.  This happens pretty much all the time.  Other than a sulking Gary Sheffield, I don’t see how any corner OF couldn’t make the transition to 1B.  I’d see the “learning curve” of 2B to LF along the same lines as RF to 1B.

***

I don’t know how the relationship of 2B/3B has evolved over time.  It’s possible that the 2B has been better in the 70s and 80s.  But, we won’t know until we study it.


#16    2008/02/07 @ 05:33 AM

what is replacement level in this system in terms of team wins (i.e. how many games does a replacement level team win)? thank you.


#17    tangotiger 2008/02/07 @ 08:22 AM

It’s right here where I say:

“since the average team wins 81, that sets the replacement team at...”


#18    Xeifrank 2008/02/07 @ 02:15 PM

Any chance you can provide a real life example, or run through the numbers of a current player, perhaps one pitcher and one hitter in calculating WAR (and showing your work)?  Thanks.
vr, Xei


#19    Tangotiger 2008/02/07 @ 02:35 PM

Shields:
http://www.insidethebook.com/ee/index.php/site/comments/sabermetric_moves_of_the_2008_pre_season/#422

Cano:
http://www.insidethebook.com/ee/index.php/site/comments/sabermetric_moves_of_the_2008_pre_season/#429

After looking over all this, you should put pen to paper, and try out a few players for yourself.  Let me know where exactly you are stuck.


#20    Tangotiger 2008/02/07 @ 05:30 PM

I posted the following at USSM and am reposting here:
http://ussmariner.com/2008/02/06/calculating-wins-above-replacement/#comment-251472

The hard part of replacement level is deciding what that level is.

The easy part of average is that we know exactly what that level is: 4.8 runs per game in the recent past.

As I said, you can stick with average and ignore replacement completely.  Consider that the average payroll is 90MM of which around 12MM is required minimum payroll, leaving you with 78MM to play with for an average team (.500).  Presuming you allocate around 57% of your payroll to nonpitchers, that gives them 45MM to allocate for 9 full-time nonpitchers.

That means the average player will get 5MM per 162 games played.  Presume for the moment that each win (free agent, arbitration, pre-arb, on average) is worth $2.2MM per win.  (Plus of course every player gets his 400K minimum.)

So, this is what you get for a guy who plays 162 games:
$7.6MM +1 win above average (WAA)
$5.4MM +0 WAA
$3.2MM -1 WAA
$1.0MM -2 WAA
$0.4MM -2.27 WAA

And if he plays 81 games:
$5.1MM +1 win above average per 81 games (WAA)
$2.9MM +0 WAA
$0.7MM -1 WAA
$0.4MM -1.135 WAA

So, roughly speaking, a guy who is an average player for 162 games is equal to a guy who is +1 wins above average over 81 games.  How do you equate those two with 1 number, rather than necessitating carrying two numbers (his WAA, and his games played)?

Well, if you add .014 wins per game to each player, this is what you get:
First player: 0 wins above average + .014 * 162 = 2.27 wins
Second player: 1 wins above average + .014 * 81 = 2.13

As you can see, both roughly equal.  If you multiply the above numbers by $2.2MM per win, and then add $400K, you get:
2.27 * 2.2 + 0.400 = $5.4MM
2.13 * 2.2 + 0.400 = $5.1MM

And those are the numbers we got when we ONLY talked about average and never brought up replacement level.

So, both sides can go ahead and do what they want to do: use only average or use only replacement.  You end up at the exact same spot.


#21    Anthony 2008/02/08 @ 01:22 AM

"That means the average player will get 5MM per 162 games played.  Presume for the moment that each win (free agent, arbitration, pre-arb, on average) is worth $2.2MM per win.  (Plus of course every player gets his 400K minimum.)”

Which assumes that an average player is worth two wins. I’m fine with that, but within the context of an average-only discussion, how do you come to the conclusion an average player is worth two wins without ever bringing up replacement level?


#22    Anthony 2008/02/08 @ 01:27 AM

Gah, ignore that last post, I’m not thinking straight. I had meant to ask how we might go about getting the $2.2MM per win total without bringing up replacement level, but got confused in my head. The $5MM per 162 games obviously comes from 45/9. I’m an idiot.


#23    Tangotiger 2008/02/08 @ 11:03 AM

Anthony/29: actually, you have a right to be skeptical.  After all, where in the world DID that $2.2MM per win come from anyway, if I ignore replacement level talk, altogether?

Each team rakes in $200MM in revenue, on average (6 billion / 30).  The question is how much impact does each win have on revenue.  If it’s 1%, that’s 2MM per win.  If it’s 2%, that’s 4MM per win.

If you go for the 1% rule, then teams, which are spending 78MM above the minimum, are paying for 39 wins above the minimum, on average.  This would imply that the minimum win level is 81 minus 39 = 42 (or .260 ball)

If you go for the 2% rule, then teams are paying for 78/4=19.5 wins above the minimum (or .380 ball).

So, figure out how much each win generates to the bottom line, and that’s the figure to use.  I’d be surprised if the outcome of that is not close to $2.0-$2.5MM per win.


#24    Tangotiger 2008/02/11 @ 11:47 AM

wes, I’m going to continue the discussion here:
http://www.insidethebook.com/ee/index.php/site/comments/spread_in_talent/#12


#25    Tangotiger 2008/02/13 @ 11:10 AM

All the Pythag related posts have been, or will be, moved here:
http://www.insidethebook.com/ee/index.php/site/comments/more_than_you_probably_ever_wanted_to_know_about_the_pythagorean_method/

I suggest reading the main article in that blog, that goes in-depth as to Pythag.


#26    2008/02/15 @ 04:51 PM

Thanks for posting this.

I wanted to give running the numbers myself a shot, and I’ve recently been mulling over how bad Julio Lugo’s ‘07 campaign was. So, I figured, why not? I pulled out my handy-dandy cellphone calculator and came up with the following:  his .283 wOBA had him roughly as a -3 hitter, he gets +.5 for being a SS, I have him as an average fielder +0, +2.25, full time player.  So I get him at -.25 WAR in ‘07 or to be kind, a smidgen below replacement.  Does that seem right to everyone?


#27    Tangotiger 2008/02/15 @ 04:56 PM

He was in the AL, so he gets +2.5 for replacement level, making his PERFORMANCE last year, according to your post, a replacement level performance.

***

Note though that even if you perform at a replacement level doesn’t mean that you are a replacement level.  The former is a sample, and the latter is a true.  Just remember that all performances are a sample of the true, and therefore a performance is a mix of the true and random variation around that true.


#28    2008/02/15 @ 05:31 PM

Whoops. I should have double checked with the formula at the top of the page before posting.


#29    2008/02/15 @ 05:57 PM

To take this one step further…

If I’m interested in getting a rough estimate of what a players dollar value was for a specific year and comparing it with his actual salary for that same year, would using WAR and your salary chart(s) be a decent way of approaching this.  For example, if Joe Schmoe was a 3 WAR player in ‘07 and his ‘07 salary was $8 million, would it be fair to look at your ‘07 salary chart and come to the conclusion that in ‘07 his net value was $4 million?


#30    Tangotiger 2008/02/15 @ 06:07 PM

Yes, if he were a free agent.


#31    2008/03/13 @ 06:23 PM

Is it possible, when calculating batting RAA to just use league average positional wOBA instead of league average wOBA and just skip giving the positional adjustments?  Or will this still understate the defensive differences between corner and middle positions?


#32    tangotiger 2008/03/13 @ 06:32 PM

You don’t want to use positional averages, because this will force the average player at each position to be equals.

If you’ve been reading my stuff on the matter, you will see that I think it’s ridiculous to presume that the average 3B = average 2B, when considering hitting and fielding.  The avg 2B is very close in fielding to the average 3B, but the average 3B is a much better hitter.  To equate them each and every year is sloppy work.  These players aren’t paid the same, and we shouldn’t pretend that they are the same.

Or look at the DH.  Case closed right there.

Our job is to model reality.  Making the average quarterback = average offensive tackle is not reality.  And neither is all the gobbledygook that the avg 2B = avg 3B forces upon us.

Do a search on “positional adjustments” in this blog.


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