Short-Stop Analytics #1: The Death of the Sac Bunt

by Matthew de Marte – March 7th, 2018

We all know what small ball is; get him on, get him over, get him in. The fundamentals of the game of baseball your first coaches, your dad, and your elders all spoke so highly about. It was the way the game was  ‘supposed to be played,’ until all of a sudden, small ball has disappeared. The sac bunt, old-school baseball’s saving grace and defining character, has died. The following graph shows the number of sac bunts every year since 1903.

 

Numbers have definitely fueled the death of the sac bunt to just 452 by non-pitchers in 2017. This number is likely to decrease in 2018 as well.  With analytics being prevalent, teams now know how many runs they can expect to score in every situation and the percent chance they have of scoring it. With these numbers, we can see how bunting affects a team’s chance of scoring runs and their expected amount of runs scored. The following table shows the expected runs for every situation possible.

This table shows the before and after expected runs for each situation that a sac bunt is typically used in, and the how much it helped (or hurt) a teams expected runs. The before column represents the expected runs for a team in the situation where they could use a bunt and the after representing the situation if a sac bunt is executed.

Situation Before After Difference
Runner on 1st 0 out 0.831 0.644 -0.187
Runner on 2nd 0 out 1.068 0.865 -0.203
1st and 2nd 0 out 1.373 1.352 -0.021

In every situation a sacrifice bunt may be used, a teams average run expectancy decreases! It does not make sense to purposefully decrease the number of runs you are expected to score. Taking away any hitter’s chance to do damage is foolish, especially in today’s game where teams rely on the home run more than ever to score. Of course, hits do occasionally occur on sac bunts, but the risk is too much. It is a better strategy to allow your hitter to swing away. So, you can see if you are managing based off trying to maximize your team’s scoring output, bunting is never the ideal situation. This next table shows a team’s percent chance of scoring in every possible situation (Table is from data between 1984-1994).

Runner 0 out 1 out 2 out
Empty 27.5% 15.9% 6.7%
1_ _ 43.5% 27.6% 12.8%
_2_ 63.3% 41.4% 22.4%
12_ 63.6% 42.5% 23.1%
_ _3 83.7% 66.7% 27.5%
1_3 87.0% 65.3% 28.6%
_23 86% 68.6% 27.7%
123 88.2% 67.8% 32.1%

The following table shows the before and after chances of scoring in each bunt situation. It also shows the difference in percent chance of scoring for each situation.

Situation Before After Difference
Runner on 1st 0 out 43.5% 41.4% -2.1%
Runner on 2nd 0 out 63.3% 66.7% 3.4%
1st and 2nd 0 out 63.6% 68.6% 5.0%

With runners on 2nd and no one out, and 1st and 2nd with no one out, the chance of scoring slightly increases. The sac bunt, in these terms, is not entirely useless then. However, that does not mean a team should use it. When implementing an effective strategy throughout the game, it is better to employ a strategy based off expected value (or runs in this case) because you are trying to maximize your run production rather than just the chance of scoring one run. If it is late in a game and a hitter who may be struggling or not a quality hitter, that is when you play the percentages, and it might be more beneficial to move runners over, as tying or securing a slight lead late in a game is the goal. Still, the use of the sacrifice bunt is extremely limited, and that is why bunting rates have plummeted.

For clubs today trying to maximize their run-scoring opportunities, front offices and coaching staffs understand bunting is not going to do that. Especially with home runs being hit more than ever, it is vital to give hitters the opportunity to do damage and not give the other team automatic outs. In a late-inning situation with a struggling or weak hitter, it may be beneficial depending on the situation if a team is playing for a run to bunt. This situation happens far too little to emphasize sacrifice bunting as a significant offensive weapon. Instead, the sac bunt is a dying strategy that has been left behind in an era of baseball where teams continue to leap towards new frontiers and continue to change how we play this beautiful game.

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