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June 20, 2010 Between The NumbersWalking Justin Morneau
I attended a wild ball game yesterday afternoon between the Phillies and Twins at Citizen’s Bank Park. The Twins emerged victorious by a score of 1310 in eleven innings, with a number of shocking lead changes along the way. However, perhaps the most shocking thing to me in the game was the decision made in the eleventh inning when Charlie Manuel elected to have Danys Baez intentionally walk Justin Morneau with a runner on first base and one out, putting the goahead run in scoring position. Jon Rauch was due to hit after Morneau, and with the bench depleted, the Twins had no choice but to let him bunt. The resulting sacrifice put two runners in scoring position with two out.
To actually believe that Morneau should not have been pitched to in that situation, Manuel must have some pretty strong beliefs about how good Justin Morneau is. Given that a walk or a single by Morneau is likely to be followed up by a sacrifice from Rauch that leaves the teams in the same situation as if the Phillies had intentionally walked him (second and third, two outs), the real question was what the odds were that Morneau would hit an RBI double or a home run compared to the odds that Baez would be able to retire him. Supposing for simplicity that Rauch is a sure third out if Baez can retire Morneau, the Phillies odds of winning the game would have improved from 50 to 64 percent in such a scenario. However, and RBI double followed by a Rauch out would give them only 17 percent chance, and a home run and a Rauch out would leave them with just a nine percent chance. Again, for simplicity, assuming that both are equally likely and even that catcher Joe Mauer would even score from first on any double, this means that Morneau getting an RBI extrabase hit would give the Phillies a 37 percent drop in their odds of winning compared to a 14 percent improvement if Morneau is retired.
For this to be wise, Morneau would need to have a 29 percent chance of getting the RBI extrabase hit on at bats that he neither walks nor singles. Even during this great season for him, this has only happened 18 percent of those at bats, and the inseason PECOTA projections would see this having only a 16 percent chance of happening on nonsingle, nonwalk atbats. For comparison, Morneau hit home runs on 39 percent of swings in the 2007 and 2008 home run derby, meaning that Charlie Manuel must have thought that Danys Baez is closer to a home run derby pitcher than an average American League pitcher to conclude that the intentional walk is a good idea. Even with the outcome of the inning as a nagging counterpoint, that sounds pretty hard to believe.
Matt Swartz is an author of Baseball Prospectus. 12 comments have been left for this article.

Matt, I don't follow how you arrive at the 29% figure leading off the final paragraph.
If they IBB him and Rauch bunts, they have a 49% chance of winning. If he hits a single or regular walks, it's about 49% chance anyway. So you just need the odds of an RBI hit (which gives them a 13% chance) weighted by that probability by the odds of an out (which gives them a 64% chance) weighted by that probability to equal 49%.
0.49 = (p) * (0.13) + (1p) * (0.64)
p = 0.29
So a mix of a 29% chance of ending up with a 13% chance of winning and a 71% chance of ending up with a 64% chance of winning on average are as good as a 49% chance of winning.
Thank you for the explanation, Matt...and if someone is going to give my original comment a negative rating for asking a nonobvious question then I think it's high time for BP to eliminate ratings altogether.