Bruin Sports Analytics
Analyzing the MLB "Sticky Stuff” Ban
By: Zayne Kratz
In baseball, pitchers and hitters alike are always looking for ways to improve. For a while, pitchers have been putting different substances on their hands, including rosin, pine tar and sunscreen in order to help them get a better grip in the baseball to get more spin on their pitches. In turn, this leads to more movement, making their pitches harder to hit. On June 21st, 2021, the MLB banned this “sticky stuff”. The reason behind this ban was to combat rising spin rates which had led to lower batting averages by hitters, which is illustrated in a graphic below. As a general rule, baseball viewers like to see higher scoring games with more action, and banning the sticky stuff is a way to give the viewers what they want. With the new rule in place, pitchers can be subject to inspection at any point in the game and if they are found to be using sticky stuff they are ejected from the current game and given a 10 game suspension. It remains to be seen whether or not this will have the desired effect, and we will explore this within the article.
We will investigate the effect that this ban has had on the spin of a ball, looking at spin rate and active spin rate. To begin, it is important to define the difference between these two similar stats. Spin rate is what a baseball fan would typically think of as spin: the rate of spin of a baseball in revolutions per minute as the ball approaches the plate. Active spin rate is a bit of a newer statistic, and it looks at the amount of a ball’s spin that is contributing to the pitch movement. To get an idea of what this actually means, we can look at football, and can pretty clearly see that although a football is indeed spinning, the spin does not have an effect on how the ball moves. This would have an active spin rate, then, of 0%. When a pitcher throws a pitch with an active spin rate of 100%, they have optimal spin that is contributing to movement. Most pitchers, as we will see, do not have 100% active spin, and it is certainly the case that different pitches can yield different active spin rates, similar to how different pitches have different spin rates.
Looking at active spin rate for different pitches, we can see that as a general trend, active spin rates increased between 2019 and 2020, most likely due to the increase in pitch analysis, where based on data pitchers can change grips and arm angles in order to get better motion on their pitches, and leading to better active spin rates. Between 2020 and 2021, when the sticky stuff ban took place, active spin rates seemed to hold constant, possibly meaning that the amount that active spin rate was increasing was counterbalanced by the adjustment to not having the sticky stuff. However, looking from 2021 to 2022, active spin rates returned to their previous increases, so it is possible that pitchers have started to adjust to the rule change.
In this graph, much more so than that of active spin, it is easy to see the effect of the sticky stuff ban. Each year through 2020 there was a pretty steady increase in spin rates, again illustrating how pitchers were able to design their pitches to get more rotation and more movement for each of their main pitches. It is very notable, then, that there is a pretty sharp decline in spin rates for all pitches between 2020 and 2021, right around the time when sticky stuff was banned. This is what we would expect to see given the rule change. Spin rates from 2021 to 2022 seem to remain about the same meaning either that pitchers have reached their ceiling of spin rates without sticky stuff, or that they are taking some time to get adjusted to not having any grip assistance, with this scenario being more likely than the former. It will be interesting to track whether pitchers can bounce back, increasing their spin rates, or whether they have truly reached their ceiling.
We have now seen the effects that the ban of sticky stuff has had on pitchers' spin rate, but keeping in mind that the purpose of this rule change, we’ll take a look at the stats the MLB was trying to change and see if the rule change has had the desired effect.
In 2022, the MLB saw the lowest runs scored total since 2015, not including the 2020 COVID year. The league also posted the lowest total batting average since 1968. In this respect, the removal of the sticky stuff failed. However, the league strikeout rate also went down, so there were more balls put into play, which would make the games more exciting for viewers.
It is worth noting that this was the first full year with the rule change, so it will be interesting to see whether these stats are outliers of a new trend or whether they are the norm.
On June 21, 2021, the MLB implemented a rule change which banned pitchers from the use of “sticky stuff”, a composite of sunscreen, pine tar and other foreign substances. This rule change was put into place with the goal of hitters more of an advantage to make the game more interesting to viewers. The change certainly has affected pitchers, whose spin rates have dropped since the rule change, and similarly have had their strikeout rates drop as well. However, the ban has not yet had the desired effect, in that batters posted lows in batting average and total runs scored in 2022. Over the next few years, we will see whether 2022 was merely part of the ups and downs of hitting statistics through the years, or whether the ban of the sticky stuff did not have the intended effect.
Baseball Almanac, Inc. “League by League Totals for Runs Scored.” Baseball Almanac, https://www.baseball-almanac.com/hitting/hiruns4.shtml.
“Active Spin: Glossary.” MLB.com, https://www.mlb.com/glossary/statcast/active-spin.
“Statcast Search CSV Documentation.” Baseballsavant.com, https://baseballsavant.mlb.com/csv-docs.
“Statcast Search.” Baseballsavant.com, Link to Search Parameters
“Major League Batting Year-by-Year Averages.” Baseball, https://www.baseball-reference.com/leagues/majors/bat.shtml.