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Win Probability: Game 108

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Here is the Win Probability graph for the Mets' 12-9 loss to the Brewers on Thursday (click to enlarge).

(What the hell is this Win Probability stuff anyways?)

A few notes about WPA:

- WPA stands for Win Probability Added
- A positive WPA indicates a positive contribution towards a victory
- A negative WPA indicates a negative contribution towards a victory (or a positive contribution towards a loss)
- Both teams start with a win probability of .500, or 50% (a 50-50 chance of winning)
- The losing team will have an aggregate WPA of -.500
- The winning team will have an aggregate WPA of +.500

What immediately stands out is Roberto Hernandez and his -1.108 WPA (Win Probability Added). I don't know that I've ever seen a WPA that low. How bad was he? If the Mets were virtually guaranteed a victory (1.000 WP) and one player single-handedly turned that victory into defeat, they would still only have a WPA of -1.000. Roberto Hernandez was 11% worse than that!! Basically, Bert blew much of the game, twice.

A quick note: I've actually been told that it's impossible for a player to have a WPA of less than -1.000 (or more than 1.000), and it does make sense if you consider the difference between one situation and another as a single play. The problem with this game was in the top of the ninth. Technically, Jenkins' single and Weeks subsequently getting thrown out at home should have counted as a single, net negative play (-.045 WPA).

This is where I diverge. I counted this as two plays: one, a -.262 attributed to Hernandez for the RBI single by Jenkins that tied the game at nine. I considered Woodward's throw home to nail Weeks at the plate as a second unique play, a +.218, all attributed to Woodward. As a result, Hernandez gets -.262 instead of -.045 (the net difference between the plays), and is thus able to catapult beyond the -1.000 WPA mark. In any event, I sent an e-mail for some clarification to Studes (from The Hardball Times and Baseball Graphs), who is the de-facto expert on this subject. I will let you know what he has to say about this scenario.