Quality of Pitch (QOP) is a statistic that measures the quality of a baseball pitch. QOP was developed by Jarvis Greiner and Dr. Jason Wilson of Biola University, in California, as a method to objectively measure the quality of a pitch. QOP is derived using a linear regression model based on the different components of a pitch.
Contents
GI = -2.51*rise +0.51*tot.break+1.88*break.point-0.47*loc
GI = -2.51*3 +0.51*.48+1.88*21.5.-0.47*8=53.6
Birth of QOP
Jarvis Greiner, one of the main contributors to the QOP measurement, was a film major and a pitcher for the Biola Baseball team in 2010. Greiner, while talking to his peers and family, realized that there wasn’t a standardized measurement for curveballs in general. In baseball games, Greiner heard commentators used phrases such as “dirty curveball” or “nasty slider” to describe curveballs. However, these descriptions were very general and did not provide real or usable information about the quality of the pitch. This made Greiner want to develop a standard method to measure and label the quality of pitches – making measuring pitches an objective process. This idea came into being during an Intro to Probability and Statistics class Greiner took at Biola University. In this class, Dr. Wilson required all of his student to conduct a statistics project. So, the very ambitious Greiner thought of combining film, baseball, and statistics, into this project.
Development
Dr. Wilson saw potential in Jarvis’ idea and offered assistance and encouragement for him to develop the Greiner Indx. Jarvis had some of this teammates pitch for him in a room with markings marked on the side of the wall, then he proceeded to film the pitches of the pitchers. Jarvis’ baseball coach, John Verhoeven (Angels, White Sox, Twins) rated the quality of the pitches according to how difficult they were to hit on a scale of 0 to 100. Greiner watched the filmed pitches and obtained the measurements from the pitches, which were initial height, breaking point, max height, and final location. Greiner, along with his teammates, did this process for 30 pitches. These rated pitches were used to derive the initial version of the Greiner Index, which is the predecessor of QOP. In other words, all the different components of the pitch will ultimately determine the “quality of the pitch.” The formula for the QOP was derived using a multiple regression model. “The rise and loc coefficients are negative, while the break.point, vert.break, horiz.break, and MPH are all positive. This makes sense, because a rising pitch and bad location make for a low quality pitch whereas a big break and fast speed make for a good quality pitch” (Wilson).
The Greiner Index (GI) is calculated with the following formula:
GI = -2.51*rise +0.51*tot.break+1.88*break.point-0.47*loc
GI = -2.51*3 +0.51*.48+1.88*21.5.-0.47*8=53.6
Definition of coefficients Rise: number of inches the ball rises vertically to the maximum height Break.point: the horizontal distance (in feet) from the release point to the maximum height Tot.break: the number of vertical feet from the maximum ball height to the point it crosses the plate Loc: the number of inches above (positive) or below (negative) the batter’s knee
The first formula is the general formula for the Greiner Index. The second formula is the Greiner Index formula for a single pitch, with a 3 inch rise, 0.47 foot total break, 21.5 break.point, and 8 inch location change. Using these numbers, the Greiner Index would be 53.6 points. “Rating, is on a scale from 0 to 100 for the quality of the curveball thrown. In the data, Rating was measured from a low of 18 to a high of 75, giving a range of 75 – 18 = 57. The model is only valid for predicting Rating within the range of the data, 18 to 75. Going beyond this range would be extrapolation, which is not justified by regression models” (Wilson).
After extensive testing, it was clear that the model followed a zero intercept model and does not contain any quadratic relationships. In addition, the p-value obtained from the model for all coefficients was less than 10^-5 (except rise, which is 0.005), and adjusted R^2 = 0.957. This shows that the model fit was excellent and represented the data well.
After obtaining the Greiner Index, Dr. Wilson then proceeded to upgrade the Greiner Index to develop QOP. In particular, the final location was upgraded to include two dimensions; speed and horizontal break was added; and the model was generalized to include all pitches (not just curveballs). The formula for QOP is patent pending and has not been made public. There are several key factors that can affect QOP. Here are some examples: increased rise will lower QOP, whereas increased total break, increased late vertical break, increased horizontal break, closeness to corners of strike zone, and increased velocity will all increase QOP. Dr.Wilson used baseball data provided by Carl Sievert’s pitchRx package in R to run this new data for QOP. Since QOP is measured by breaking a pitch down into its individual components and analyzed from there, the pitch’s quality does not depend on the batter’s batting performance. This means that QOP is solely based on the pitch itself, is objective, and is batter independent. This method can be considered objective, because a standard yardstick is used to measure the quality of different MLB pitches. Some critics say that the QOP isn’t accurate because it is based on the Greiner Index, which is based on the ratings of Biola’s baseball coach and not “truly objective.” Despite this critique, QOP is objective in the sense that the same “measuring stick” is used to measure all the pitches.
Vision
Greiner’s hope for QOP is that it would be the standard measure to rate the quality of pitches in baseball. Just like how kmh or mph is the standard unit of measure for the speed of a pitch, Greiner hopes that QOP can be used to measure the quality of a pitch. Greiner hopes that, in the near future, the MLB would adopt QOP and use it as the standard measure for a pitch’s quality. Commentators and coaches could use QOP to determine how efficient a player’s pitches are on a given match and allow coaches to make managerial decisions. There are many applications to QOP. One application for this concept is the “QOP gun,” just like how the speed of a baseball pitch can be calculated by a speed radar gun, Greiner hopes that in the near future, there will be “QOP guns” that can measure the QOP of a pitch. Having a standardized and objective method in determining a pitch can help improve the way in which scouts search for prospective pitchers. Teams can use QOP to consider if the pitcher would be a valuable asset to their team. Since important information such as ERA is based off a pitcher’s ability to pitch and reduce the amount of points scored by the opposing team, QOP could be useful in determining a pitcher’s future ERA. These future ERA predictions can allow teams to be able to know which pitchers would be helpful for their team and would be able to make these teams make more informed decisions on which players they should invest their resources on. With further research, QOP might have correlations with injury and will allow for greater advancements and discoveries in the sports medical field.