Monday, June 8, 2009

Regarding Bunting

Ken Macha is taking a lot of flak from the great unwashed mass of baseball fandom that enjoys pointless sacrifice. I would point them to Baseball Prospectus’s book, Baseball Between The Numbers, and specifically to James Click’s chapter, “When is One Run Worth More Than Two?” which begins on page 127. In that chapter you will find useful bits of info like this:

If the team sacrifices when behind by one run, then instead of increasing the chance of winning, it decreases the win expectation by 3.6%.


Now, some of you are probably saying things like “Yeah, but what about Jason Kendall? He sucks anyway.” Well, we have research on that too. With a runner on first and no one out, a bunt makes sense (meaning the team’s chance to score at least 1 run will increase) if the batter’s line is worse than .177/.192/.153.* Jason Kendall is bad, but his .216/.307/.265 still makes swinging away the correct strategy.

I recommend reading the whole chapter and the whole book.

*If you’re wondering how slugging can be lower than BA, the numbers were calculated independently.

9 comments:

  1. I wish so much that Macha had dropped the percentages on the reporters instead of the bullshit "I play to win on the road" nonsense.

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  2. Thanks for posting this. I have previously seen the stats on the lower chance of winning with bunting but I did have the "What if the batter is Jason Kendall?" question. Good stuff.

    That batting line makes it a marginal choice even if the batter is a pitcher! That part is surprising to me.

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  3. No prob. I'd really recommend reading the chapter and the whole book. In terms of win expectancy I think it makes some sense. When you are trailing, outs are more precious than they normally are. Click makes the point that a sacrifice is actually less damaging when you're down by 3+ because your odds of winning are so low to begin with. (It's still damaging though.)

    "Second, it's significantly worse (italics original) to do so (sacrifice) when down by 1 or 2 runs than when down by 3, largely because the win expectancy is so low when a team is down by 3 that there just isn't much to lose by sacrificing. More important, the worst (still original) time to sacrifice is when a team is down in a close game, even when that deficit is only 1 run.

    By the way, my copy of the book is autographed by Nate Silver.

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  4. And there should be a closed quote after "1 run".

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  5. I agree in general, but these win expectancies can't be treated as gospel, since they are averages of myriads of situations. For instance, if the batters coming up behind the potential bunter aren't very good, that must make bunting worse. If tony gwynn is on deck, that must raise the % impact of the bunt. If the batter is a ground ball machine, that must also raise the impact of the bunt b/c it lessens double play possibility. Or if batter is super fast scrub, bunt can be good because of % chance it turns into a hit or error. i doubt bunting jason kendall can be too much of a mistake as long as the hitters coming up behind him are good.

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  6. Do the BP calculations presume the success of the sacrifice bunt?

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  7. There's a chart for that too. It's pretty comprehensive. It even takes into account the % of bunts that result in double plays and outright singles.

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  8. And to Jon, yeah, I agree with all of that. I defend non-bunting strategies vociferously just because I feel like many people have a love affair with bunting regardless of situation. It's not gospel, but it's a good guideline to work off of.

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  9. I was thrilled to see flak spelled correctly

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