Wednesday, April 18, 2012

Bunting in Baseball, Part II--The Sacrifice

To continue the analysis of bunting I began with the first part, this post will review sacrifice bunts only. Sacrifice situations are those that occur with a runner on base (any base) and with less than two outs. Strictly speaking, it's entirely possible that not every one of these is a true sacrifice situations, since there have been instances as I review the play-by-play data where a batter did bunt with a runner on base and less than two outs but the at-bat wasn't scored as a sacrifice hit. Whatever. This table shows sacrifice hitting in 1950 and 2011:

It must be noted that in 1950, play-by-play data was available for only about 80% of games (click here to see a complete list of games that did and didn't have play-by-play data--scroll down two or three times), but that's not really important here. I'm introducing a concept that I'll define as a successful sacrifice bunt, which would be:


It's fairly self-explanatory, but we can define success for our purposes as either a successful sacrifice bunt, reaching on an error AND the baserunner advancing or a hit. We can argue on a case-by-case basis that sometimes this isn't truly a success, but for our purposes, two things have occurred--either:
1. The runner was moved along
2. The bunter didn't make an out
We have no reason to suspect that the 80% of plays that are represented by the 1950 numbers are not representative of the season as a whole, so one could make the plausible argument that the art of the sacrifice might be decreasing. I don't possess the statistical savvy to test if the difference between 1950 and 2011 is statistically significant, but any time a difference of 10 percentage points is seen in almost anything, chances are it's heading down that road. Several things jump out in the data:
1. Striking out while attempting to bunt increased by a factor of 10, implying that not only was this an unsuccessful event, but contact wasn't even made. An increased incidence of striking out while attempting to bunt can be considered a marker of decreased bunting skills.
2. I think we can all agree that grounding into a double play while bunting is about as bad as it can get, and it would appear that the incidence of that went down by about a factor of two. I won't even begin to try to explain it (because I can't), and the number of events in either year makes it relatively unimportant.
3. Even in a sacrifice situation, where the infield might be assumed to be in better position to field a bunt (and I don't know this), bunting for a hit still works--it's not as effective as with the bases empty but still batting near .300 is nothing to view with contempt.

It's not perfect, and doesn't measure the ULTIMATE measure of a successful bunt, which would be if one or more of the runners on base score in the inning. The only way to accurately measure that would be to review the individual innings in which these 3,600+ occurrence happened, and that's a bit much. As I get more data from different years, we can measure the utilization of bunting in different baseball eras, as well as the relative success--a brief look shows that the reached-on-errors were roughly equal even though the number of bunts doubled, implying an increased ability to defend against it.

There's nothing earth-shattering in any of this, just a deeper understanding of the numbers that go into the conventional wisdom. I'm not suggesting bunting is a bad idea or that player's abilities bunting are in decline, but just reporting what the numbers show. In the right situation, it still works, and if we are indeed entering a new era of decreased offense, it will probably be used more.

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