The Louisiana State University Shreveport Pilots are an NAIA team in Shreveport, Louisiana competing in the Red River Athletic Conference. This article was written by Brent Lavallee and David Howell. Brent Lavallee is the Head Coach of the Pilots and David Howell is the Director of Player Development, Director of R&D, and Assistant Pitching Coach.
With the rise of affordable bat sensors, we no longer have to rely on only the eye test when it comes to evaluating swings. Gone are the days of attempting to evaluate a hitter’s progress based on the small sample of fall games, or how well they seem to be hitting flips at the end of the season. Even the days of measuring exit velocity during tee work with a radar gun are comparatively basic with what can be accomplished with a sub-$200 Bluetooth sensor.
At LSU Shreveport, we started using Blast Motion sensors this fall, which are placed on the knob of a bat and measure metrics such as bat speed, attack angle, rotational acceleration, and more. The sensors work by taking into account the characteristics of a bat (length, weight, etc.) and derive swing metrics when hitters make contact.
Our application of sensors consists of using them to get an assessment of each hitter’s swing in as close to a game environment as possible, using those metrics to set goals for hitters, and then evaluating progress using the same conditions as the initial assessment to see if programming led to desired changes. We decided to place our focus on two metrics: bat speed and attack angle.
Why Bat Speed and Attack Angle Matter
As measured by Blast, bat speed is defined as the speed of the barrel at impact. Max Dutto, Alex Caravan, and Dan Aucoin at Driveline have shown average bat speed to be highly correlated with average exit velocity as well as production, making bat speed a valuable point of focus in training. In short, a high level of bat speed is similar to fastball velocity in that it is a prerequisite to playing at a high level. From the same article, estimates of major league bat speeds range from between 65-80 mph. Because of this, we gave our hitters a target median bat speed of 70 mph with a 34-inch bat or 73 mph with a 33-inch bat.
We chose to focus on attack angle as an objective measure of swing plane. Attack angle is the angle of the bat relative to the ground at impact (not to be confused with vertical bat angle, which is the tilt of the bat at impact, with 0 being parallel to the ground and -90 being perpendicular to the ground). A positive attack angle means the bat is traveling upwards at contact, while a negative attack angle means the bat is traveling downwards at impact. Given practically all pitches thrown overhand approach the plate on a downward trajectory, a positive attack angle maximizes both the amount of time the bat can be on plane with the pitch and the likelihood a flush hit ball will result in a hard fly ball or line drive.
So, with these two metrics as focal points, we developed a process to collect baseline readings to assess each hitter’s swing, place them into groups based on their strengths and deficiencies, and then retest metrics to evaluate progress.
Data Collection Process
Readings were taken off a Hack Attack pitching machine set to a fastball at 90-92 mph at a right-handed pitcher’s release point in our indoor facility. We attempted to use a pitching Rapsodo to control for fastball spin as well, but it wouldn’t read off the machine. On our Hack Attack, we were able to get in the desired velocity range at what appeared to be a reasonable spin rate by setting the side wheels one tick below 7 and the bottom wheel one tick above 8. Hitters were instructed to think 2-0 fastball and to do damage on the pitch. We recorded baseline readings consisting of three rounds of eight swings, and then placed hitters into preliminary groups based on their strengths and deficiencies.
Target Ranges to Shoot for in Bat Speed and Attack Angle
Referencing the article from Driveline above again, estimates of average major league bat speeds (estimated from models trained on paired Blast and Hittrax data) fall in the 65-80 mph range. For this reason, we aim for our hitters to be able to average above 70 mph with a 34/31 bat or 73 with a 33/30 against high velocity so that they have the ability to both catch up to competitive velocities and hit for power.
Attack angle can also be estimated at the major league level by finding the range where each hitter’s hardest hit balls fall using data from Baseball Savant. Looking at each hitter’s average launch angle of the top eighth of their hardest hit balls has been shown to be a solid linear predictor of attack angle. By subtracting 5 degrees from these estimates, we can get an idea of where attack angles fall at the major league level. Furthermore, if we filter for hitters with average exit velocities within 2 mph of the MLB average and 100-plus balls in play and compare their attack angles to production by xWOBA, we can get an idea of what comprises an optimal range (R^2 value of .13, p-value .0005):
When balls are put in play by hitters with average exit velocities at the MLB level, a positive relationship exists between estimated attack angle and xWOBA on balls in play. Few average attack angles fall close to 20 degrees, with the vast majority appearing to fall between 5 and 15 degrees. There doesn’t appear to be a noticeable drop in production on the higher end of the range of estimated MLB attack angles.
Presumably, a large part of the advantage in a higher attack angle is the increased likelihood that a squared-up ball will result in an extra-base hit. Even if a hitter doesn’t possess professional bat speed, they still will likely benefit from a higher attack angle due to the smaller dimension of college baseball fields, so long as the increase in attack angle doesn’t come at the expense of making contact.
Let’s look at the relationship between attack angle and how frequently a batter makes contact when they swing at the major league level (R^2 value of .06, p-value of .001):
There appears to be somewhat of a relationship between higher attack angles and higher swing and miss rates. There could be several reasons for this.
If hitters with higher attack angles tend to have higher-value balls in play (as measured by xWOBA), hitters with lower attack angles will have to make up for their less advantageous swing path (in terms of generating high-value balls in play) by whiffing less often. With that being said, there still is likely a tradeoff between raising attack angle and raising swing-and-miss rate. However, given the added benefit of more potential extra-base hits on balls in play and smaller fields at the college level, erring on the higher end of the range of attack angles may be worth it.
With this in mind, we felt a range of attack angles between 8-23 degrees was appropriate for hitters to aim for.
Programming Hitters Based on their Blast Metrics
Here’s how we grouped our hitters:
GROUP A – Transition to Game Environment Group: This group had an average bat speed of 70 mph or higher with a 34 bat (or over 73 mph with a 33), and an average attack angle between 8-23 degrees.
GROUP B – Attack Angle Focus: This group had an average bat speed of 70 mph or higher with a 34 bat (or over 73 mph with a 33), but did not have an average attack angle between 8-23 degrees.
GROUP C – Bat Speed Focus: This group had an average bat speed below 70 mph with a 34 bat (or 73 mph with a 33), but they did have an average attack angle between 8-23 degrees.
GROUP D – Bat Speed and Attack Angle Focus: This group had an average bat speed below 70 mph with a 34 bat (or 73 mph with a 33), and they had an average attack angle outside of 8-23 degrees.
While we used a similar core of drills across groups, modifications to the drills and different focuses were placed for each group.
Training Bat Speed
Our bat speed programming consists of 2-3 days a week of a hand-loaded, head-loaded, and under-load bat progression. We limit our players to a maximum of 36 swings a day with these training bats. Once we used the Blast metrics to group our hitters based on swing characteristics, we altered a little bit of the plan for each group. For example – Group C needed to improve on overall bat speed, so they were prescribed more swings each day with the under-load bat. Their programming looked like this: 2-Hand, 2-Head, 4-Under, 2-Game. Group B, which had a focus on improving attack angle, was programmed a greater focus on the overload bats (4-Hand, 4-Head, 2-Under, 2-Game) to help them with barrel depth and barrel awareness/control.
Training Attack Angle
Another major part of our hitting progression is incorporating Driveline Hitting Plyo Balls 2-3 times a week. These balls are a great tool for several reasons. Because the balls are sand-filled and tend not to travel far unless hit flush, they are great tools to force hitters to get on plane with the path of the ball and hit it square.
Once we separated our hitters into their groups, they were given a prescribed Plyo Ball regimen. We limit our hitters to approximately 24 swings a day with the Plyo balls. Each group has the ball fed to them a different way and their intentions on where they were trying to hit the ball would change. Groups B and D would have all of their Plyo Balls fed to them from over top of the L-screen. This forces hitters to adjust their Attack Angle to hit the ball flush and off the top of the cage. Group C hits all of their balls coming from a flat flip and their focus is to hit the ball as hard as possible back where it came from. Group A, which is our transition group, gets alternating feeds. One comes from over the L-screen with the intentions of being hit off the top of the net, and the next ball is fed on a line and hit back where it came from. This allows hitters in Group A to feel out adjustments in attack angle to pitches with different approach angles.
Additional Programming Staples
Every day towards the end of their progression, hitters see coach pitch batting practice or high-velocity machine work to get comfortable against game velocities. Using a Hack Attack pitching machine, we can easily allow each of our hitters to face multiple rounds of fastballs at 90-92 mph, or even curveballs and sliders if we desire. Facing the most difficult and game-like portion of the hitting progression challenges our hitters to maintain any swing adjustments they made during drill work. Throughout drills and machine work, swing count is defined and monitored to ensure hitters aren’t overworked.
Thirteen of 19 hitters saw an increase in bat speed, with 10 of the 13 most likely not by chance (p-values below .5). Fifteen of 19 hitters had an increase in attack angle, with 11 of 15 changes likely not being due to chance. As a team, there was an increase in bat speed of .08 mph and an increase in attack angle of 2.5 degrees, with p-values < .000 for both.
Group A saw a decrease in bat speed of .2 mph (p-value .329), and an increase in attack angle of 1.6 degrees (p-value .039). Group B saw an increase in bat speed of 2.0 mph (p-value .001) and an increase in attack angle of 3.6 degrees (p-value .000). Group C saw an increase in bat speed of .3 mph (p-value .008) and a decrease in attack angle of .4 degrees (p-value .975). Group D saw an increase in bat speed of 1.0 mph (p-value .002) and an increase in attack angle of 3.9 degrees (p-value .000).
Analysis and Takeaways
Overall, results have been positive over the month we’ve started to implement our new process of programming hitters. We can say with confidence that our hitters have improved their bat speed and increased their attack angle as a whole. Higher bat speed will result in harder hit balls and higher attack angles will result in squared up balls to have a greater chance to be high line drives and fly balls, which result in extra-base hits and home runs.
Five hitters jumped more than 2 mph in bat speed from their baseline readings. Of those five, four ended with averages above 70 mph and also had increases in attack angle of more than four degrees. These hitters are in a far better position to have highly productive seasons than they were just one month prior.
We can also see how the number of players in each group have shifted since baseline readings were taken (note median bat speed and attack angle were used to form groups rather than using the mean, see definition of groups above):
The goal for hitters is to move into Group A (meet a minimum bat speed threshold and fall within an ideal attack angle range) and to avoid Group D (bat speed and attack angle deficiency). We can see there was an increase in the number of hitters in Group A from 5 to 7 and a decrease in the number of hitters in Group D from 7 to 4. This, coupled with the fact several hitters in Groups B and C are very close to cracking Group A, is extremely promising and shows the prescribed programming has been driving the desired changes.
Having documented each practice plan and the drills used, we can also begin looking for ways we can better help our hitters who failed to move out of Groups B, C, and D. The ability to objectively track each hitter’s progress helps us learn what is and isn’t working for different hitters and allows us to continuously improve how hitters are instructed.
In future posts, we’ll look to evaluate how swings change in response to different pitch types and explore how we can best help our hitters prepare to see a mix of different pitches. As always, we’ll record data against competitive velocities and share our progress.
In the end, the reason we choose to track bat speed and attack angle is because of the connection between the metrics and in-game performance. The ability to better understand how our hitters are progressing and responding to different programming gives us an advantage over teams that over-cue hitters, spend massive amounts of time on tee work, and remain ignorant of whether they’re actually helping hitters improve.
Our hitters have put in hard work to make progress this fall and we’re beyond excited to see what they can do in the Spring.
This article was originally published on www.cargocultsabermetrics.com.