Impact of each release parameter on pitch location in baseball pitching

Understanding whole-body inter-personal dynamics between two players using neural granger causality as the explainable artificial intelligence

Understanding the dynamics of complex, whole-body interpersonal coordination behavior in humans is an important subject in behavioral science. However, due to the challenges of analyzing complex causal relationships among multiple body components with conventional techniques, this area remains underexplored. To address this issue, this study proposes a new analytical framework that attempts to understand the underlying causal structures behind each joint movement of individual players using neural Granger causality (NGC) as the explainable artificial intelligence (XAI). In the NGC analysis, causal relationships were defined as the size of the weight parameters of the first layer of a machine-learning model trained to predict the future state of a specific time-series variable. To verify this approach practically, we conducted an experiment with 16 pairs of expert baseball pitchers and batters, and input datasets with 27 joint resultant velocity (13 pitchers' and 14 batters' joints) were generated and used for model training. The results revealed that significant causal relations exist among intra- and inter-individual body components, such as "the batter's hands have a causal effect from pitcher's throwing arm." Although the causality from the batters to the pitcher's body is significantly lower than that from the pitchers to the batter's body, it exhibits a significant correlation with the performance outcomes of batters (R2 = 0.69). These results suggest the effectiveness of the NGC analysis for understanding whole-body inter-personal coordination dynamics and, more broadly, the XAI technique as a new approach for analyzing complex human behavior from a perspective different from conventional techniques.

Two-dimensional trial-by-trial error correction for accurate baseball pitching

Throwing an object accurately at a target position at high-speed repeatedly is a specific human motor skill. The arrival position of the thrown ball is approximately determined by its physical state at release. In high-speed baseball pitching, reducing the variability in the ball's elevation/azimuth angle of the velocity at release (release angle) is particularly necessary to reduce the variability in the vertical/horizontal arrival position. However, as there is always variability in human movements, which increases as the speed increases, decreasing the variability is an issue. This study focused on one strategy, trial-by-trial error correction, which is to correct movements in the subsequent trials facing an undesirable outcome. Fourteen skilled baseball pitchers' intertrial changes in the elevation/azimuth release angle of 30 balls were analyzed together by transition probability analysis in addition to a separate analysis using the autocorrelation function. The results showed a difference in error correction depending on the state and direction, and Friedman's test for the transition probability from state to state showed a significant difference in the rank means [chi-squared = 25.79, df = 15, p = 0.04]. In addition, this suggests that the pitchers with large variability in the release angle made fewer corrections in the horizontal direction. These findings indicate that trial-by-trial error correction can be a strategy to decrease variability however, complicated factors are involved in error correction.

Impact of slip distance between fingertips and ball on baseball pitching performance under different friction conditions

This study aimed to investigate the finger-ball slip distance in baseball pitching under different finger-ball friction conditions and to demonstrate how slippage affects pitching performance. 6 experienced pitchers were instructed to throw 4-seam fastballs at approximately 36.1 m/s (130 km/h) toward a target behind the home base. The finger-ball friction conditions varied and included no application, water application, rosin powder application, and pine resin application. The finger-ball slip distance was estimated from images of the fingertips and ball during the ball release process captured by a high-speed camera (2000 frames/s). The slip distance was significantly affected by the finger-ball friction condition. The distance in the water application condition (21.6 ± 5.3 mm) was 142.3% and 163.8% greater than that in the rosin powder (8.9 ± 3.5 mm, p = 0.022) and pine resin application conditions (8.2 ± 2.2 mm, p = 0.002), respectively. In the ball release process, except for the water application condition, the ball was released by hooking the fingertips on the seam, and the ball slid against the fingers. However, in the water application condition, slip occurred throughout the ball release process. The slip distance was negatively correlated with the ball speed and ball spin rate and positively correlated with the horizontal and vertical ball arrival locations. Our findings will provide new insights into the understanding of how a ball is released in baseball pitching under different friction conditions and will lead to improvements in pitching performance.

Pitching kinematics have direct and indirect effects on pitch location in NCAA baseball

Kinematics and release parameters are important factors of throw location; yet an understanding of their relationship has yet to be achieved. This study sought to explore this relationship. Kinematic data were collected for 77 collegiate pitchers. Fifty-seven kinematic parameters were included in path analyses for horizontal and vertical plate locations. Release angles were set as mediating variables (MED) between independent and dependent variables. Eleven kinematic variables directly (13 indirectly) affected the vertical plate location, while 23 kinematic variables directly affected the horizontal plate location (10 indirectly). Linear mixed models revealed that lateral trunk flexion at ball release (R 2=0.908, BIC=-598, ICC=0.528) best explained vertical plate location. Trunk flexion at foot contact (R 2=0.944, BIC=-607, ICC=0.776), mediolateral center of mass displacement at foot contact (R 2=0.974, BIC=-573, ICC=0.918) and ball release (R 2=0.967, BIC=-593, ICC=0.865), and pelvis rotation at ball release (R 2=0.965, BIC=-588, ICC=0.895) models were identified for the horizontal plate location. Results indicate that the relationship between pitching kinematics, release conditions, and throw location is complex. Biomechanics can influence release parameters, which in turn impacts the throw location. This work may serve to understand better how biomechanics influence performance.

Positional relationship between ball and fingers for accurate baseball pitching

Accurately throwing an object to a target position repeatedly is one of the specific human motor skills. The final arrival position of a thrown ball can be determined by its physical state at release. In baseball pitching, reducing the variability of the velocity angle of the ball at release (release angle) is important for reducing the variability of the pitch location. Although previous studies have suggested that hand and finger movements are important for accurate throwing, their relationship with the release angle has not yet been investigated in detail. This study focused on the positional relationship between the ball and fingers, which is considered to be closely related to ball movement as an action point of the force, and examined its relationship with the variability of release angle. To obtain accurate finger positions relative to the ball without impeding movement or sensation, an automatic image recognition technology based on deep learning was employed. This approach revealed a noteworthy correlation between the lower middle finger positions prior to acceleration peaks and the reduced variability in release angle, emphasizing the importance of consistent finger positioning during the pre-release phase. This finger positioning of the pitchers with low variability in the release angle is suggested to be robust against the spatial variability of ball movement.

A new category of "Aha!" driven by touch: A grip sensation into the directional seam on a baseball

We report an "Aha!" experience which differs from conventional Aha's studied over a century in psychological science. The Aha we introduce is driven by touch instead of the visual and verbal modalities widely studied to date. It can occur when gripping a baseball, with a simple input that the red seam on the ball has a direction. Aided by a symmetry analysis and subsequent survey over literature, we show how our mental and physical representation of a baseball can change suddenly by the seam direction and unravel the factors that make the tactile sense into a joyful-and-insightful sensation. Our study sets a new category of Aha driven by touch, opens a new path to investigate the role of touch in our cognition process, reveals the seam direction as a new degree of freedom in baseball aerodynamics and pitching mechanics, and deepens the insights into throwing a baseball from our fingertips.

Estimating flight trajectories of breaking balls from four-seam fastballs

It is widely acknowledged that understanding the physical mechanics of the flight trajectories of four-seam fastballs and breaking balls is crucial for players and coaches to enhance pitching performance. The characteristics of the flight trajectories of four-seam fastballs and breaking balls have been revealed; however, the relationship between them has not been examined. Here, we show the characteristics of the flight trajectory of breaking balls from the four-seam fastballs. We found that the direction of the deviation of the curveballs could be generally predicted from that of the four-seam fastballs. We also found that the limits of the deviation of the sliders can be determined from the direction of the deviation of the four-seam fastball. This study revealed the deviation of the breaking ball from the four-seam fastballs, which clearly showed the differences in the characteristics between curveballs and sliders. This study moved forward with the description of the physical properties of each pitch type and allowed us to obtain valuable insights and practical implications.

Ulnar Collateral Ligament Reconstruction Does Not Decrease Spin Rate or Performance in Major League Pitchers

BACKGROUND

Ulnar collateral ligament reconstruction (UCLR) is commonly performed in Major League Baseball (MLB) pitchers, with variable reported effects on velocity and traditional rate statistics. Currently, no studies have evaluated spin rate in the context of return to play (RTP) after injury. Greater spin rate has become increasingly sought after in the baseball community, as it is believed to be a vital aspect of pitch effectiveness.

PURPOSE/HYPOTHESIS

The purpose was to evaluate the effect of primary UCLR on fastballs (FB) and sliders (SL) of MLB pitchers in terms of spin rate, velocity, hard-hit rate, and whiff rate. It hypothesized that the post-UCLR FB and SL spin rates, velocity, and whiff rate would be significantly decreased versus their pre-UCLR levels, while the FB and SL hard-hit rates would be higher in comparison with pre-UCLR levels.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In total, 42 pitchers who underwent UCLR and returned to MLB play were identified from public records from 2016 to 2019. The Statcast system was used to collect spin rate, velocity, hard-hit rate, and whiff rate for 4-seam FB (4FB), 2-seam FB (2FB), and SL for pitchers in the preinjury year as well as the 2 years after return from UCLR. Data were analyzed using the appropriate statistical tests.

RESULTS

A total of 36 pitchers met the inclusion criteria, and 31 of the eligible 36 players (86.1%) were able to return to MLB pitching (RTP). There were no significant decreases for 4FB, 2FB, or SL in spin rate, measured in revolutions per minute (rpm), when comparing preinjury levels with the first and second seasons after return. There was a significant decrease in velocity for the 2FB in the first season (92.9 vs 93.7 miles per hour [mph]; P = .045) but not the second season (93 mph; P = .629) after RTP in comparison with pre-UCLR levels. For the 2FB, there was a significant increase in spin rate between preinjury and RTP season 2 (2173.5 vs 2253 rpm; P = .022). For the SL, there was a significant increase in spin rate between preinjury and RTP season 2 (2245.1 vs 2406 rpm; P = .016).

CONCLUSION

A cohort of MLB pitchers who underwent UCLR and returned to the MLB level demonstrated no significant decreases in the spin rate, velocity, whiff rate, or hard-hit rate of 4FB, 2FB, or SL at 2 years after UCLR.

Using Advanced Data to Analyze the Impact of Injury on Performance of Major League Baseball Pitchers: A Narrative Review

Major league baseball (MLB) pitchers are at risk of numerous injuries during play, and there is an increasing focus on evaluating their performance in the context of injury. Historically, performance after return to play (RTP) from injury has focused on general descriptive statistics, such as innings or games played, or rate statistics with inherent variability (eg, earned run average, walks and hits per inning pitched, strikeouts per 9 innings, or walks per 9 innings). However, in recent years, MLB has incorporated advanced technology and tracking systems in every stadium, allowing for more in-depth analysis of pitcher-specific data that are captured with every pitch of every game. This technology allows for the ability to delve into the pitching performance on a basis that is more specific to each pitcher and allows for more in-depth analysis of different aspects of pitching performance. The purpose of this narrative review was to illustrate the current state of injury recording for professional baseball pitchers, highlight recent technological advances in MLB, and describe the advanced data available for analysis. We used advanced data in the literature to review the current state of performance analysis after RTP in MLB pitchers after injury. Finally, we strived to provide a framework for future studies to more meticulously assess RTP performance given the current available resources for analysis.