Should Batters Have Two or More Swings?

Photo Credit: Mark J. Rebilas/USA TODAY Sports

In the world of baseball, both pitchers and batters are constantly strategizing to gain an edge. Pitchers carefully choose their pitches and arm angles based on the situation, while batters make subtle adjustments to their stances or even switch to lighter bats against particular pitchers. But are batters fully utilizing the spectrum of swing varieties to maximize their performance?

In this post, I will explore whether batters can enhance their productivity by employing launch-based, high-velocity power swings in hitter's counts and contact-based, lower-velocity level swings in pitcher's counts.

I’ve taken inspiration from Mike Petriello's article titled “What you need to know about Statcast bat tracking”, finding his analysis of swing speeds and attack angles very insightful.

I especially find his featured heatmap, illustrated in Figure 1, very interesting. As we can see, the swings with the highest wOBACON are the uppercut swings; they also have the highest attack angle, swing speed, launch angle, launch distance, hard hit rate, barrel rate, and batting average on contact.

In most cases, when a batter can generate and make contact with a high swing speed, he prefers using an uppercut swing. There are exceptions, such as situations where the batter needs to ensure a sacrifice fly or hit a ground ball to advance a runner. The problem with the uppercut swing, however, is that it can struggle to make contact.

Figure 1: Mike Petriello’s heatmap of batter attack angle, swing speed, exit velocity, launch angle, and launch distance

The flattest swing, on the other hand, has the highest batting average on balls in play (BABIP), despite having the lowest attack angle, swing speed, exit velocity, launch angle, launch distance, hard hit rate, and barrel rate. In an 0-2 or 1-2 count, if a batter’s aim is to simply make contact and put the ball in play, a flatter swing results in the highest batting average.

To determine whether a particular swing type is optimal in a given situation, I’ve looked at whiff rates (swing and miss %) for each type of swing. Since we don’t have comprehensive data on batter attack angles on Statcast yet, I will use Petriello’s results to map the relationship from launch angle to batter attack angle.

I’ve grouped the 230,000 pitches put in play in 2023 by batter and launch angle to find the average launch angle and standard deviation of launch angle for each hitter. I filtered for the 517 batters who had at least 75 batted balls with recorded launch angles. The approximation for the relationship is illustrated in Figure 2.

Figure 2: Approximating Batter Attack Angle (y-axis) from Launch Angle (x-axis)

Of the 517 batters, Joey Gallo had the highest average launch angle of 28.55 degrees and Colton Cowser had the lowest average launch angle of 4.03 degrees.

The two hitters with the lowest standard deviation in launch angle were Luis Arraez (.354 AVG) and Freddie Freeman (.331 AVG). Arraez and Freeman finished 1st and 3rd in the MLB in batting average, respectively. Jackie Bradley Jr. (.133 AVG) and Brad Miller (.214 AVG) had the highest standard deviation in launch angle.

Next, I grouped the 700,000 pitches in 2023 by batter and whiff rate, and then merged this dataset with the launch angle dataset. The average launch angle is mapped to average attack angle using the quadratic function in Figure 2 to see the relationship between attack angle and whiff rate.

To my surprise, I found very little correlation (r=0.02) between a batter’s average attack angle and his whiff rate. Hence, I decided to break down the pitches by zone - low, middle, and high - to see if a correlation between a batter’s average attack angle and whiff rate exists at a more granular level.

The results were as follows:

Figure 3: Slight negative relationship between attack angle and whiff rate on low pitches (r=0.098)

Figure 4: Slight positive relationship between attack angle and whiff rate on middle pitches (r=0.14)

Figure 5: Moderate positive relationship between attack angle and whiff rate on high pitches (r=0.17)

As we can see in Figure 3, 4, and 5 above, uppercut swings yield a slightly lower whiff rate on low pitches, a slightly higher whiff rate on middle pitches, and a moderately higher whiff rate on high pitches. Since uppercut swings have the highest wOBACON and a slightly lower whiff rate on low pitches, it certainly makes sense for hitters who can generate enough swing speed to use uppercut swings on low pitches.

On middle pitches and high pitches, however, batters need to weigh the benefit of the higher xWOBACON on uppercut swings with the cost of the increased whiff rate.

When faced with a two strike count, where the whiff penalty is highest, using a flatter swing may result in more production than an uppercut swing on pitches at the top of the zone.