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Kai Franke

An Analysis of the 4 Man Outfield

MLB and its teams have been very progressive in terms of adjustments due to analytics in this century so far. Moneyball led to more emphasis on OBP, hitters have started to pull the ball more, and technologies have changed how pitchers attack hitters. There have also been changes in positioning with new data for the shift, and with that has come with some extreme ways the players are being moved around the entire field. But none of the new shifts that teams have used come close to the oddness and extremity of the four man outfield. Used mostly for lefty flyball hitters, it has been used to take away extra bases in a "no doubles defense". This has people wondering though, is it really a good way to position a defense? Well in this article, I figure out whether or not this shift has benefits or if it doesn't help.


First of all, the reason this shift is used with lefties more than righties is because teams can shift the third baseman into the outfield when a lefty hits, but can't move the first baseman when a righty is up. This causes a huge difference between the amount used between righties and lefties. Also, as mentioned earlier, the main use of this shift is to prevent extra base hits, and with more players hitting the ball in the air, to prevent hits from those batted ball types. Let's see how the shift works against flyballs and line drives (Savant):

The three shifts used are the aforementioned fourth outfielder, the strategic shift, and the normal outfield. The strategic shift is just the outfielders shifted to the hitters' pull side. I filtered out batted balls for both hands, and as thought, most of the fourth outfielder shifts went to lefties. The sample size for them is not very big though, so these results would get more stable as time goes on. Since the shift is used for extra base hits, I first decided that I wanted to figure out what percent of batted balls ended up for doubles and triples, but not homers as the shift can't do anything about them. This first test shows that doubles and triples happen more frequently with the four man outfield than any of the other shifts at 16.4%.


However, the sample size for that shift is too small to make conclusions from counting stats without any more context, such as batted ball information. Expected stats compared to the actual stat needed to be added to see exactly how hard those balls were hit and the likelihood of them ending up creating damage. If the shift benefitted the defense, the expected stat minus the actual will be positive, and if it benefitted the hitters, it is negative. At a first look, the batting average for the fourth outfielder benefits the hitters, as xBA-BA is positive, but if you look deeper, you'll see that the minimal right handed batted balls actually drag down the total to negative. The left handed batted ball majority is positive, so I am going to listen to the left handed hitters due to it being dragged down by a sample size. Batting average doesn't show how the fourth outfielder shift fares against extra base hits though, so slugging percentage and wOBA will be better for this.


For the slugging percentage, it fares the defense much better than the other shifts as the difference of xSLG and SLG is .167 bigger than the next highest shift. This shows that extra bases are diminished with the how hard the ball is getting hit, which is exactly what the fourth outfielder shift is designed to do. The better overall stat, wOBA, also shows the same results as SLG. The xwOBA - wOBA is .034 higher than any of the other shifts, again showing that it lowers the frequency of extra base hits more than the other shifts. The only problem with using these two stats though, is that they include home runs in their equations, but the shift doesn't affect homers. I believe that the results wouldn't change much because the difference is so significant between the shifts that they have to have an effect on the balls in play.


As shown above, it is difficult to get extra base hit with this defense, so I wanted to see how they happened against it. I took all of the doubles hit off of the shift (since there were no triples hit), and then looked at the averages of exit velocity, launch angle, and distance. This turned out to be an average ball hit at 91.8 mph, launched at 26.7 degrees, and hit at a distance of 288 feet. This doesn't really gives a whole ton of information, though, as we don't really know which direction the balls were hit and it is for sure better to see what actually happened. I decided to look through each of the eleven doubles hit off of the shift to see what typically would happen.


The main results that appeared to happen on doubles were balls that hit the wall/hit behind the fielders, liners to the corner, and misplays. An example of a ball that got behind the fielders is this one from Matt Olson (All videos are from Savant):

This was very close to hitting the wall and wasn't catchable as it was hit in the gap. These gap hits don't happen often against the shift, but if it was hit about 10 feet shorter, it would've been caught. The next one, a ball hit the wall, is from Joey Gallo:

This hit was very close to a home run and really shows, along with the last one, that hitting the ball far will really help with getting hits off of this shift, which is obvious. For balls hit in the corner, I decided to use this example from Justin Smoak, who has had to face four outfielders more than anybody else in baseball:

This ball wasn't hit very high with a 15.8 launch angle, so that really helps here. If it was hit higher, it probably could've been caught. Finally, here is Cody Bellinger getting off of a misplay from Jarrod Dyson of the Arizona Diamondbacks:

This would've for sure been a single if it was played much better, but these videos show that when extra bases happen, the ball is hit behind a fielder, low to the corner, or misplayed, and unlike a lot of normal doubles, it is much harder for a player to hit balls into the gap which we most often see from doubles, which shows that this positioning makes it harder to get them.


With more data coming to baseball year after year, Major League Baseball will see even more strategies to get more outs and win more games. Initially with the four man outfield, it appears to do what it was designed to do, which is to prevent extra base hits. However, we do not have a huge sample size, so this result could change as we get more teams to do this, which I do see happening. I am convinced that it does help with taking away extra bases though, because this shift takes away a ton of space in the outfield where a ball would typically drop in for extra bases. So as the shift continues to evolve and change, expect the four man outfield to appear more often.


Videos and stats from Baseball Savant

Cover Photo from Bat Flips and Nerds

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