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Myth Busting with Bat Tracking Data


Ken Griffey Jr. swinging away, CCed by Liscense 2.0

As detailed in my fellow writer Perry Nadreau’s article, Baseball Savant’s new bat tracking data has added an incredible tool to the repertoires of analysts, writers, and everyday fans of the game alike when it comes to breaking down the best and worst hitters in the league. If you don’t fall into one of those categories, or if you do but haven’t yet delved into the world of bat tracking data, then I highly suggest you take a look at Perry’s piece so that you don’t get lost reading this one. These new metrics have enabled us to validate long debated ideas about how hitters generate power in a swing. As well, it displays why some batters are better than others at making contact with the baseball, as the metrics quantify how fast a batter can move the bat through the zone as well as how long the barrel of the bat is in the zone. In this article, I am going to test a couple of those theories and see if the new data at my disposal supports or demerits them.


It has long been claimed that left-handed batters have longer and flatter swings than their right-handed counterparts. Most baseball fans, especially those of older ages, immediately think of the sweet swinging Ken Griffey Jr. when asked to think of a left handed hitter. The Swingman indeed had a long swing, due to the huge amount of separation he could create by opening up his left elbow, which dually created plenty of room for him to pull his hands through the zone and get the barrel to the ball. On the other hand, another famous lefty hitter in Ichiro Suzuki had an incredibly short and direct swing that turned him into one of the greatest contact hitters the game has ever seen, tallying 4,367 hits in professional baseball between Nippon Professional Baseball in Japan and Major League Baseball in the United States. Comparing these two world class hitters immediately makes us question whether this old adage about lefty swing length is true. Let’s see if the new data from Baseball Savant can settle the argument. Right off the bat (pun intended), we see that the average swing length in MLB for lefties is 7.2 feet from the start of the swing with the batter holding the bat behind their head to contact out in front of the plate. However, we also see that the average swing length of right handed hitters is 7.4 feet, 0.2 feet longer than the average left handed swing. What about power hitters vs. contact hitters for both handedness groups? Well, we know that longer swings generally yield higher bat speed due to a longer amount of time for the barrel to speed up through the swing, meaning more power output by the hitter. We also know that shorter, more direct swings are better for making contact with the ball because they allow the hitter to get their barrel on plane with the pitch quicker. So for this analysis, we will assume batters with above average swing length would have a more power oriented approach, and the opposite for those with below average swing length. In doing this, we find that the lefty power hitter group still has a shorter average swing length than the righty power hitters, measuring in at 7.5 and 7.7 feet respectively. The same once again rings true for contact hitters, with the righties leading the lefties 7.2 to 6.9 ft. All around, right handed batters have longer swings on average than their left handed counterparts, completely debunking this myth. However, grouping the two main swing types most prevalent in our game today has me curious. Are there some players who are capable of producing BOTH types of swings?


The two strike approach is a classic example of a clash between traditional baseball strategy and new age, analytically driven strategy. In the past, hitters were taught to choke up on the bat, shorten their swing, and protect the strike zone by fouling off pitches they couldn’t necessarily put good wood on, but ones close enough to be called strikes. This was seen as the best way to prevent striking out, which was the biggest problem for a hitter in an era of small ball and contact centered offenses. Nowadays however, many professional hitters are encouraged to get their A-swing off no matter the count. This is believed to create more value in the long run given the added probability of slugging an extra base hit at the expense of a similarly higher probability of striking out. However, even in today’s game, not every hitter is a Joey Gallo or a Giancarlo Stanton, which begs the question; which hitters slow and shorten their swings based on the count, or vice versa? To answer this question, we will group possible counts the hitter can face into 3 buckets. Early counts are counts where neither the hitter nor the pitcher has a clear advantage yet. These counts are 0-0, 0-1, 1-0, and 1-1, and typically see an even mix of aggressive and passive approaches from hitters. Behind counts are counts where the pitcher is behind in the count, in which hitters are typically more aggressive as the pitcher is more likely to throw strikes. These include 2-0, 2-1, 3-0, and 3-1. Finally, Finish counts are counts where the pitcher can finish the hitter off with one pitch. In short, any two-strike count other than 3-2, which we won’t use in this analysis as it has a unique status as being both a Behind and a Finish Count. For context, I'll start by stating that the average bat speed and swing length for all hitters in Early counts are 71.8 MPH and 7.4 feet. For Behind counts, the averages are 72.7 MPH and 7.4 feet. Finish counts see predictable changes in their averages which drop to 70.2 MPH and 7.3 feet. Immediately we see that the two-strike approach is very much present in today’s game, as hitters drop their bat speed an average of 1.6 MPH going from Early to Finish counts, and 2.5 MPH from Behind to Finish counts. Surprisingly however, batters did not seem to shorten their swings much as they moved into Finish counts, although there were some outliers.Jose Caballero of the Tampa Bay Rays had the largest change in bat speed from Early and Behind counts to Finish counts. Caballero slowed his bat down a whopping 4 MPH going from Early to Finish counts, and an even greater 6.9 MPH going from Behind to Finish counts, as shown in the graph below.





This must mean Caballero is elite at making contact in 2 strike counts and avoiding striking out right? Unfortunately no, not at all actually, as Caballero falls into the bottom 15th percentile in Whiff%, K%, and Contact%.




In this interesting graphic provided by Baseball Savant, we can really see the variety of swings that Caballero is capable of based on the peaks in the number of swings for each bat speed value. This graphic is an incredible way to visualize the idea that many hitters don’t have just one swing, but multiple swings, almost like a tool box, for different counts and situations in the game.When it comes to changes in swing length, a more familiar name tops the leaderboards. Willi Castro has a fairly average length swing in Early counts, but as he gets deeper into at bats, he “Willi” focuses on putting the ball in play.




As pictured in the graph above, Castro shortens his swing by a huge 0.4 feet as he goes from Early to Finish counts, and 0.2 feet as he goes from Early to Behind counts. Castro still struggles to avoid K-ing up though, as he falls into the bottom 34th percentile in K%.


Based on the results we’ve seen from both Willi Castro and Jose Caballero, it’s tough to say that slowing down the swing and shortening the bat path really makes much of a difference in preventing strike outs. However, these are the 2 most extreme batters when it comes to this strategy, and a deeper dive would be necessary to draw a more certain conclusion.


Just as in any good scientific experiment, we’ve ended our analysis with more questions than we started with. Why do righties have longer swings than lefties and why was the opposite believed for so long? Does a two-strike approach really help in reducing strike outs? And if so, what is the perfect combination of decreased bat speed and swing length to maximize contact? The good news is that with the new bat tracking data available to us, all of these questions are answerable, and I can’t wait to dive deeper and learn more about the intricacies of this great game.


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