It's been an exciting few weeks seeing all the work that's been done thanks to Statcast's expansion into bat tracking. The good thing about this game is that there is always more to learn. With the addition of bat speed and swing length, we now have a better idea of how to tell the story of a player's swing, but there is still a lot to touch on.
Back when I used the Blast Motion bat sensor every day, I was exposed to every part of the swing you could imagine. Bat speed was one of them, but that was only a scratch. There were pieces that explained my approach at different points in the swing, how long it took my barrel to meet the ball's flight, where it happened in space, and much more. For a while, the available public data focused on the outcome. What was the pitch? What was the result? What was the exit velocity and/or launch angle? With this new update, we're on the way. How fast did the player swing? How far was their swing? Now we can relate that to the effect, but more details are needed to understand the full scope of how the effects occur. That will be the focus of this piece.
First, it's important to highlight the good work that's already been done to explain the new data we have and what it tells us (and doesn't tell us) about throwing. Ben Clemens explained some applications of the new metrics and what their relationship to performance is on a larger scale. One thing Ben said that resonated with me was to think of new (and old) knowledge as inputs we should use to understand performance rather than the answers themselves. Each episode works together to tell a story, regardless of the league or player. Basically, these are pieces of information that need more context.
Related, Patrick Dubuque and Stephen Sutton-Brown from Baseball Prospectus, provided a great analysis of how to put bat speed into the context of pitch statistics, from the perspective of both the hitter and the pitcher. And there's more than just these two, including Noah Woodward's Substack post about bat speed, swing length, and understanding what they mean and how they contribute to swing.
Woodward touched on a couple of aspects of throwing that I've talked about in previous work that we don't yet have complete data from Statcast: contact point and angle of attack. Swing variation, swing order, having an A and B swing, etc. all very important to succeed at the big league level. If you have a hole in your swing, usually, pitchers will expose you, so having multiple high quality swings will set you up for consistent success, just ask Triston Casas. Swing-by-wing data on angle of attack, vertical and horizontal bat angle, and contact point will all help the public's understanding of swing variations, when and how to swing in general.
Let's start with the angle of attack. This is the angle of the bat at contact, relative to the ground. As your bat moves through space, it creates a trajectory. To increase your chances of hitting the ball in the air, the bat must be on an upward trajectory at contact, which means you must have a positive angle of attack. One aspect of swing variation creates a more precise angle of attack with varying lengths, widths, and depths. You just want to be able to use your barrel to go up no matter where the pitch is. To get a better idea of what the angle of attack looks like, let's take a look at a video from David Adler explaining the swing to Oneil Cruz:
Bat Track – Oneil Cruz 120.4 mph single (highest hit ball in MLB this year)
84.5 mph bat speed (75+ mph “fast swing” limit) pic.twitter.com/FO9gA6fqva
— David Adler (@_dadler) May 21, 2024
Although the angle of attack is officially measured as the angle of the path to contact, seeing the path leading to contact can tell us what kind of depth the hitter is creating. In this clip, the angle of the path changes as it moves from behind Cruz's body to in front of it. This illuminates how the angle of attack depends on the contact area. Generally, the more your bat is in front of the plate, the easier it is to create a straight angle of attack. However, this series from Driveline's Hitting Director, Tanner Stokey, discusses the importance of creating bat speed deep in the zone. The best hitters build up speed on hard winds. Like all aspects of baseball, swinging is about striking a balance to create high levels of bat speed and good angles of attack. You don't want to have a one-size-fits-all swing that focuses on high bat speed while ignoring the need to create proper bat angles both deep in the zone and in front of the plate.
Depending on how you start your swing and get into position, it takes time to convert your barrel into an upswing. For most hitters, the bat needs to travel a long distance to create the angle of attack that leads to proper contact. This, of course, takes more time. But, as Robert Orr pointed out last week in his piece about the relationship between pulled fly balls and swing length, longer swings aren't a bad thing; really another data point. By accessing the angle of attack, we can better tell the story of how a hitter like Isaac Paredes creates depth in his swing while often making excellent contact in front of the plate, compared to a hitter who makes front contact without the necessary creation. depth in their turns to avoid large holes.
At the same time, it is still possible to create a deeper attack angle in the batting area. In order to get there, you need to be able to perform complex movements while generating bat speed and controlling your body. Some good hitters use a lateral torso bend — leaning on their back leg just before contact — to get their barrel on a deep upward slope in the hitting position. Think Shohei Ohtani or Edouard Julien:
These two have extraordinary abilities that enable them to launch platforms high in the air to another place. With the point of contact and the angle of attack, we will be able to measure how different they are from their peers in addition to visual analysis.
Then there are hitters who create flat (but still good) angles of attack that stay in the same plane throughout their swing. They get on plane with the ball early and don't do much to change their path mid-swing. It is almost impossible to do this with swing. Juan Soto is a good example of this, even if he is stronger than other hitters with this swing style. Here's a good angle that shows what I'm referring to:
Bat tracking — Juan Soto 112.0 mph line drive single off Justin Verlander
Sitting on a curveball hanging at the top of the field pic.twitter.com/IRhdzHVMy8
— David Adler (@_dadler) May 8, 2024
Soto's vertical entry angle (the angle of the bat relative to the ground at the start of the downswing) is not far off from his angle of attack. You can see how different this pitcher is from Cruz, who is a slow giant. As a result, his bat path is upward, and his bat needs to travel a long distance to come into flight with the ball. With detailed knowledge of barrel angles at different points in the swing, we will know more about how hitters like Soto and Cruz differ from each other when it comes to landing and staying on plane.
This has been a lot of information all at once, so I'll leave you with a final report. Depending on the hitter, the angle of the path at contact can be very different from the angle of the barrel at contact (relative to the ground), known as the vertical bat angle. Although I have quoted the average vertical bat angle several times, I have always focused on putting the metric in context because it varies based on several factors. Luis Arraez and Aaron Judge may have similar exact bat angles, but that doesn't tell us anything about how different their swings are. We know the metric depends on pitch, but that alone isn't enough to explain why Judge is a starter and Arraez is a sprinkler. As we learned earlier, each data point is input and is not meant to be used alone.
There is no question that teams have been using, monitoring, and using this data to evaluate and develop players for years now, but despite all the metrics we have, information on the public side is still lacking. Ideally, in the coming years, we will gain access to more swing data to better understand the game we love.
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