Home Run Update – June 6

Measuring Home Run Production

Since home run rates have been very volatile during the Statcast era, it is interesting to see how home run production compares with the results from recent seasons. Since the carry properties of the baseball has changed over recent seasons, I have found it helpful to focus on home run rates among the balls that are hit with suitable exit velocities and launch angles. In particular, I define the “RED ZONE” region to be balls in play where the launch angle is between 20 and 40 degrees and the exit velocity is between 95 and 110 mph. For these balls, I define the “RED HR Rate”:

RED HR Rate = 100 * (HR in RED ZONE) / (Balls in play in RED ZONE).

Since home run rates typically increase as the season progresses through warmer weather, I plot the RED HR Rate for each day of the season and add a smoothing curve. Using this method, it is easy to compare 2024 with some recent seasons.

Compare with 2019

2019 was the record setting season for hitting home runs — 6776 were hit in that season. Below I compare the RED HR rates of 2019 and 2024 through games of June 5 (last night). Clearly home runs are currently hit at a lower rate in 2024 — the rates are approximately 32% in 2024 compared with the low 40’sin 2019.

Compare with 2022

In contrast, 2022 was one of the poorest recent seasons in HR hitting. The carry properties of the baseball were poor compared to other neighborhood seasons. Here’s a graph comparing 2022 with 2024 through June 5. It is interesting that the 2024 rate tends to be higher through the middle of May, and the 2022 rate is higher in the second half of May.

Compare with 2023

People are most interested in changes from the previous 2023 season. Here’s a graph comparing 2023 with 2024. In this period, the 2023 RED HR rate tends to be higher than the 2024 rate although the rates are pretty close.

Takeaways

Tom Tango concluded recently on Twitter that with respect to home run hitting “2024 is in the ballpark of 2022, and not far off from 2023”. This graphical analysis seems to confirm Tom’s statement. Certainly, home run rates will tend to increase as the weather gets warmer, but I think we would see similar comparisons at the end of the season.

R Notes

It was relatively easy to produce these plots. The lubridate package will convert the character dates to a special date format. Once one has computed the day to day HR rates, then by using the ggplot2 system, one plots the date against the HR rate. If one creates a data frame with the date, rate and season variables, then ggplot2 will create separate smoothing curves for different seasons by using color = season as one of the aesthetic variables.