Don't try to outsmart a clutch home run
Win Probability Added and WAR


If you're not familiar with Win Probability Added, here is a primer from Dave Studeman.  Excerpted:


... the concept is simple. Let’s say our batter in the bottom of the ninth hits a single to put runners on first and third with no outs. This increases the Win Probability from 71% to 87%, for a gain of 16%. So, in a WPA system you credit the batter +.16 and debit the pitcher/fielder -.16. If you add up every positive and negative event from the beginning to the end of a game, you wind up with a total for the winning team of .5, and a total for the losing team of -.5. And the player with the most points will have contributed the most to his team’s win.


A simpler example, you hit a 2-out 0-on walkoff homer to raise your team's chances of winning from 56% to 100%, you get "credit" for giving your team 0.44 wins.  

... of course, they subtract, too -- if you strike out with the bases loaded, you're liable to get an 0.10 deduction or whatever.  For example, Rickee Weeks' homer was glorious Sunday, but it is slightly overbalanced (so far) by all the times he whuffed. 

There were some quips in the Shout Box about Nelson Cruz scoring 0.0 WAR to date, but deserving 1.0 WAR for Sunday alone.  Well, here's the math on it through 6 games:

Mariner Net Wins Batted In
Boom Stick 0.71
Ack Attack 0.26
Seth 0.22
Robby 0.20
MLB Logo 0.18
Hawt Corner 0.10
Rickee -0.11
Austin Jaxon -0.34
LoMo -0.46


Since the Mariners have won +3.00 games, Dr. D will go out on a limb and assume that the pitching and defense gets credit for +2.33 of those wins.

Compare also the TEAM TOTAL to that of NELSON CRUZ.  ... Boomstick is #2 in the American League, a skosh behind Miguel Cabrera's 0.73.  However, Cruz' WAR is flatlined at a nice round 0.0.  According to WAR, he's completely worthless; according to the scoreboard and standings, he is worth more than every other Mariner put together.

So it's worth a moment.

SSI doesn't say that Nelson Cruz is a major star.  SSI tilts against the windmill that is constantly spinning the idea that RBI are irrelevant.  Attempt to outsmart a clutch home run at your peril, babe.


Is WPA predictive?  Doesn't matter.  It is descriptive.  We are not talking about what Cruz mighta done or coulda done or shoulda done, but what he did done.  What he did done, first week, is provide the differ'nce between a 1-5 record and a 3-3 record.


In terms of predictability, WPA is more interesting as it pertains to relievers.  Here's the table, courtesy of the wonderful stats compilation site that is Fangraphs.


  • Rested Medina
  • Carson Smith (obviously)
  • Tyler Olson
  • Charlie Furbush (necessarily)


  • Bartender


  • Farquhar
  • Rodney


It's early, of course, very early.  Note, however, that SSI was wringing its hands pre-season on Farquhar and Rodney.  I mean, where did Farquhar come from anyhow?  How long did George Sherrill last?

We'll see.  There are arms down there.  And two more of recent interest.


The Mariners, having come through a slow hitting week, are on pace for 189 homers.  Bet the over or the under?







All teams stay each game with a 50% chance to win. The Mariners are 3 and 3 which means the team had a net ZERO WPA...not 3


Meaning I guess the pitchers and fielders had a -0.67 as of the 6th game.  Thanks for the catch.
Placing Cruz' 0.71 WPA into that much higher relief :- )

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