August 23, 2009

Why is Bunting Usually a bad idea?

Filed under: Uncategorized — wwinston @ 9:18 am

For over 40 years baseball experts have realized that when an average batter is up, bunting is a bad idea. Yet at the Indianapolis Indian AAA game which I attended last night (had a great time by the way) 4 bunts were attempted! Several of these bunts involved the pitcher (probably a poor hitter) but to enlighten those of you who do not know why bunting is usually a bad idea, let’s go through the simple logic.

   Suppose there is a runner on first on none out. How many runs does an average MLB team score in an inning is this situation? The answer is 0.93 runs. Now let’s bunt and suppose the bunt succeeds. Now we have a runner on second base and one out. How many runs does an average major league team score in an inning with this situation? The answer is 0.71 runs. Therefore the “success” of the bunt has cost our team ) 0.22 runs. This should make it clear why the bunt is usually a bad idea.

   Of course, if the batter is a poor hitter (like a pitcher) the bunt might make sense or if the score is tied and our goal is to simply score a single run the bunt might be a good idea. For more discussion of baseball decision-making see chapter six of my new book Mathletics, which will be released by end of  August.

1 Comment »

  1. A manager’s biggest fear is for a hitter to hit into a double play.

    Man on 1B, no outs = .93 runs
    Man on 2B, 1 out = .71 runs

    Man on 1B, no outs + swinging away = .10 chance of double play >> No men on base + 2 outs.

    (The .10 chance is conjecture, but worth looking into). Perhaps the repercussion of a double play is worth the -.22 sacrifice that you give up for a bunt, as in, nearly guaranteeing that your runner advances.

    Comment by shlomo — September 30, 2009 @ 9:42 pm

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