Should Players Try to Bunt for a Hit More?

This post will look at bunting for a hit and try to identify if it is a skill that can efficiently and effectively increase offensive production, and answer the general question of, should players bunt more?

Is Bunting for a Hit a Skill?

Before we answer the ultimate question of whether or not players should bunt more, we need to first identify whether or not bunting for a hit is a skill to begin with.

This is where data becomes an issue, but we should be able to make do.

Before 2002 there are no records on FanGraphs of bunt hits, so I looked at all qualified hitter seasons from 2002 to 2014 in which a player bunted three or more times in a season—since most players go a whole season without a bunt, three bunts or more in a season puts a player in the top fifty percentile for bunt attempts in a season.

From there I looked at the year-to-year correlation of a player’s bunt hit percentage—bunt hits divided by bunts (i.e. a player’s batting average on bunts)—for the entire population. Mind you, we only have record of the amount of times a player bunts, not the amount of times a player attempted to bunt for a hit. So in all reality, a player’s bunt hit percentage would be higher if we were able to tease out the amount of times that they laid down a sacrifice bunt from their total bunts. However, from the data we are still able to find a .33 year-to-year correlation on bunt hit percentage for our population of hitters.

Takeaway: bunting for a hit is a skill.

Should Players Bunt More?

Now that we’ve answered the question of whether or not bunting for a hit is skill, we can circle back to our original question of whether or not players should bunt more.

Because we want to have a large enough sample of attempted bunts for bunt hit percentage (BH%) to stabilize, we will look at all qualified hitter totals (i.e. multiple season totals), not individual seasons, from 2002 to 2012.

To answer our question we need to look at the expected value gained for a player when they have an at bat where they don’t attempt to bunt—a regular at bat—and subtract it from the expected value gained in at bats where they attempt to bunt for a hit—a bunt hit attempt.

To come up with the expected value of a regular at bat we have to look at the linear weight value added per plate appearance of a player’s at bats from 2002 to 2012, or their entire career value if their whole career falls within that period. We then multiply that linear weight value per plate appearance by probability that they achieve one of those outcomes.

Here’s the formula for Expected Value of a regular at bat (xRA):

  • =((((1B-Bunt Hits)*0.474)+(2B*0.764)+(3B*1.063)+(HR*1.409)+(HBP*0.385)+(IBB*0.102)+(UBB*0.33))/(PA-Bunt Attempts))*((1B-Bunt Hits)+2B+3B+HR+BB+HBP)/(PA-Bunt Attempts)

This formula looks much more complicated than it actually is, but you’ll be able to click into the cells in the live excel document below and visually see how the values are computed. All of the decimals that are part of the formula are linear weight values, which you can find here.

We need to go through the same process to figure out what the expected value added is for a player on a bunt hit attempt—the average value added with a bunt times the probability of a successful bunt hit (BH%).

I was unable to find the linear weight value of a bunt hit, but we do have a sufficient substitute. A bunt hit essentially adds the same value as a base hit with no runners on base—.266 runs per inning. A single with no runners on base is a good proxy for the happening of a bunt hit. Like a base hit with no runners on base, a bunt hit offers no opportunity for a runner on base to score or advance past the next base in front of them. Short of looking at box score data to find the average amount of runners that scored per inning after a successful bunt hit, which will need to be done for a more conclusive answer to our question, we will use the average linear weight value of a single with no runners on for each of the out states as our linear weight value (i.e. I averaged the linear weight value of a single with no runners on base and no outs, a single with no runners on base and one out, and a single with no runners on base and two outs to get the average linear weight value; this is not the exact way to get the linear weights value of a single with no runners on base, because there are undoubtedly a different amount of singles with no runners on base that occurred for each out state, but this should be close).

This is the formula for expected value gained on a bunt attempt (xBA):

  • Bunt Hit Average (bunt hits/total bunts)*.266 (our estimated linear weight value for a bunt hit)

Now that we’re able to come up with the expected value added for a player in a regular at bat (xRA) and the expected value added for a player on a bunt hit attempt (xBA), we can subtract the two values from each other—xRA minus xBA—to see which players have lost the most value per plate appearance by not bunting.

This chart shows the players with a minimum of ten bunt attempts that have lost the most value by not bunting (i.e. which players have the biggest difference between their expected value gained from a regular at bat and a hit attempt):

Click Here to See Chart with Results

Bunts: Bunt attempts

Bunt Hits: Hits on bunts

RA%: Chance that a positive offensive event occurs, outside of bunt hit

BA%: Chance that a player gets a hit on a bunt

xRA: Expected value added from a regular at bat

xBA: Expected value added from a bunt attempt

Net Value: xRA minus xBA

Implications

This research doesn’t mean to suggest that all players who have a higher expected value added on a bunt attempt than they do in a regular at bat should bunt every time. Carlos Santana gets a hit in 78% of the at bats where he bunts, but he has only attempted 14 bunts in his career, so we don’t have a large enough sample of bunt attempts to know what his actual average on bunt attempts would be; this goes for most if not all of the players on this list. There is most likely an inverse correlation between BA% and bunt attempts (i.e. the more you try and bunt for a hit, the less likely you will get a hit as the infield plays further up on the grass).

This research means to suggest that players have not reached the equilibrium for bunt attempts (i.e. they haven’t maximized their value). Players should increase the percentage of the time they bunt until their xRA and xBA are the same; at this point their value will be maximized. The more a player with a negative net value tries to bunt for a hit, the more expected value he will add. This will happen until his expected value added from a bunt falls beneath what he is able to achieve through a regular at bat; this happens when the defense starts to defend him more optimally, they align for the bunt hit, and his BH% falls. Once this occurs he will force the defense to play more honestly—the infielders will have to play farther in on the grass—and increase his expected value added in a regular at bat as more balls get past the infield from shallow play.

What’s interesting is that there are two different types of players on this list. The first type of player is the type that you would traditionally think of as player who would try and bunt for a hit: the speedster with very little power. The second type of player is the player who, as a result of the recent, extensive use of defensive shifts, has a high BA%—batting average on bunt hits—because the defense is not in a position to cover a bunt efficiently: Carlos Santana, Carlos Pena, Colby Rasmus, etc.

The voice for the question about why players don’t try to beat the shift with bunts down the third base line has grown louder, but there still hasn’t been a good answer as to why it hasn’t been done more; the evidence seems to suggest that it is valuable and should be done more. I’m not able to confirm that the 11 hits that Carlos Santana had on bunt hits came when the defense was in a shift, but I think it would be somewhat unreasonable to believe that he was able to beat out a throw to first on a bunt hit attempt when the defense was in a traditional alignment more than a few times.

Carlos Santana Spray Chart

Carlos Santana’s spray chart take from Bill Petti’s Spray Chart Tool

The image above is a spray chart of Carlos Santana’s ground ball distribution as a left-handed hitter; the white dots are hits and the red dots are outs. This chart suggests that it would be advantageous for teams to shift against Santana when he bats left-handed. I would argue that because of Santana’s success—his high BH%—at bunting for a hit, he should do this more, which will generate more value by itself, and increase the value generated in regular at bats as he forces the defense to change their defensive shift against him from the increase in bunt attempts. However, once he reaches the equilibrium, any further changes may ultimately be a zero sum game.

There are no silver bullets to get more runners on base, but there will always be more efficient, undervalued ways to achieve that goal. This research has proven that bunting for a hit is underutilized, and once more work is done to tease out sac bunts from a player’s bunt hit attempts and calculate an accurate BH%, along with the generation of linear weight values for a bunt hit, we will have a more definitive answer for what a bunt hit is worth.

Devon Jordan is obsessed with statistical analysis, non-fiction literature, and electronic music. If you enjoyed reading about pitcher value in Fantasy Baseball, follow him on Twitter @devonjjordan.





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Dildo Backends
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Dildo Backends

Isn’t BU just bunts in play, so all the negative value of foul/missed bunts in PAs that didn’t end with a bunt in play is miscategorized?

Dildo Backends
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Dildo Backends

Players attempt to bunt plenty of times and just foul it off or miss it completely. Every time that happens, it’s a negative run value (since it’s just an additional strike). When those PAs end with something other than a later bunt in play, you’re counting that PA in the “didn’t try to bunt” category (because BU doesn’t count foul/missed bunts), even though the failed bunt attempt decreased the value of that PA. So your value for “swing away” is artificially depressed by the missed bunts and the true value for choosing to “swing away” is always going to be… Read more »