Park factors are one of the many unique elements of baseball as, unlike the other major professional sports, each ballpark has different dimensions and features that play a role in determining whether a given park is friendlier to hitters or pitchers. Park factors expand beyond field dimensions and wall height, as elements such as altitude, wind patterns, and surrounding buildings all play a role in affecting how play occurs on the field.
Last week, I wrote my Going Deep article on how the elevated strikeout environment of T-Mobile Park, potentially due to the park’s unique batter’s eye, impacts the Mariners’ offensive output. Upon further analysis, an increase in whiff rate on four-seam fastballs appeared to be a major contributor to this lack of offense at the stadium, which is backed up by the fact that some Mariners pitchers like George Kirby and Luis Castillo produce elevated swing-and-miss on their four-seamers when pitching at home.
These findings inspired me to take a look at how certain pitch types generate swing-and-miss at each ballpark across Major League Baseball to attempt to identify whether there are any trends or patterns that suggest that a stadium’s park factors might contribute to an elevated swing-and-miss environment for a given pitch. Since the 2024 season is still ongoing, I will be taking a look at the whiff rates at each ballpark per pitch type from the 2021, 2022, and 2023 Major League Baseball seasons. This will hopefully create a large enough sample size to account for random variance as well as pitcher/hitter quality. Before taking a look at the whiff rates at each stadium, it is important to take a look at Statcast’s three-year rolling park factors to provide some context as to which parks have induced elevated strikeout environments in recent seasons.
As shown by the table above, Tropicana Field, American Family Field, and T-Mobile Park were the three ballparks with the most elevated strikeout environment over the past three seasons. This makes intuitive sense, as Tropicana Field is the only fixed-roof stadium in the Majors while American Family Field and T-Mobile Park are both retractable roofs, providing pitchers with relatively stable environments to pitch in. Truist Park and Yankee Stadium are surprising entries on this leaderboard, and perhaps a deeper analysis of each pitch type’s whiff rates at these parks will provide insight into why this phenomenon occurs at both ballparks.
Fastballs
To simplify this analysis for a broader interpretation, I bucketed all pitch types into three classifications: fastballs, breaking balls, and off-speed. All four-seam fastballs and sinkers thrown from 2021 to 2023 are considered “fastballs” for this analysis. While there is a debate to be had over whether cutters should be considered a fastball or a breaking ball (which can lead to a very nuanced discussion), I have decided to classify cutters as a “breaking ball” alongside sliders, sweepers, and curveballs for this analysis. Changeups and splitters will be classified as “off-speed”. All other pitch types (such as eephuses and knuckleballs) have been discarded for this analysis. Let’s take a look at the ballparks that had the highest fastball whiff rates from 2021 to 2023:
As shown by the table above, there appears to be a strong correlation between fastball whiff rate and strikeout park factor as four out of the five parks with the most elevated strikeout environment appear in this table. This makes intuitive sense, as despite recent trends, fastballs are still the most commonly utilized pitch in Major League Baseball. Therefore, the results produced on four-seam fastballs will have a strong influence on the overall park factor of the given ballpark. One surprising ballpark on this leaderboard is Guaranteed Rate Field, home of the Chicago White Sox. Fastballs generate a 22.5% whiff rate at Guaranteed Rate Field while the strikeout park factor at the stadium is near league-average at 102.
In my article detailing the strikeout environment at T-Mobile Park, I referred to its deceptive batter’s eye in center field as a potential reason for the elevated fastball whiff rate at the ballpark. This past February, Davy Andrews of FanGraphs conducted some comprehensive research attempting to measure “pitch visibility” at each Major League stadium based on contact rate, chase rate, and umpire accuracy. As a result of this research, Guaranteed Rate Field ranked as the 6th most difficult ballpark in Major League Baseball to accurately see pitches. Perhaps the batter’s eye at Guaranteed Rate Field is creating deception to hitters which is causing them to struggle on four-seam fastballs.
Similar to the previous table, all five of the ballparks with the lowest fastball whiff rate are among the six ballparks with the most suppressed strikeout environment in all of Major League Baseball. Coors Field being at the top of this table is no surprise, as the extreme altitude where the park is located has a significant impact on declined fastball performance. The inclusion of Chase Field at the bottom of this list is interesting, given that the park has a retractable roof which is typically connected to an elevated strikeout environment. Chase Field, Kauffman Stadium, and Coors Field all have deep outfield dimensions, and I wonder if the distance of the batter’s eye from home plate has a role in positively affecting the hitter’s fastball perception. Perhaps the air circulation pattern is different in Chase Field than in other retractable roof ballparks, although this is difficult to prove without further information. In general, fastball performance has a significant impact on determining the overall strikeout environment of a given park, and a pitcher must develop and/or utilize other pitches if they want to have success at Coors Field, Kauffman Stadium, Chase Field, PNC Park, or Busch Stadium.
Breaking Balls
As mentioned earlier, I have classified cutters, sliders, sweepers, and curveballs as breaking balls for the following analysis. Let’s take a look at the ballparks that had the highest breaking ball whiff rates from 2021 to 2023:
As shown by the table above, some new ballparks appear on the leaderboard for the top five breaking ball whiff rates. Truist Park is the best ballpark in generating breaking ball swing-and-miss by a considerable margin, with a 35.1% whiff rate on breaking balls from 2021 to 2023. Angel Stadium of Anaheim, Dodger Stadium, LoanDepot Park, and Wrigley Field also produce elevated swing-and-miss environments for breaking balls. It is interesting to see that both ballparks located in Greater Los Angeles appear on this leaderboard which makes me wonder if the environment in this area (perhaps weather-related effects) plays a factor in breaking balls generating more swing-and-miss. loanDepot Park has had a reputation as a pitcher’s park since its opening in 2012 due to its large outfield dimensions and retractable roof, which causes no surprise that it appears on this leaderboard.
As shown by the table above, Oriole Park at Camden Yards and Nationals Park rank as the two ballparks with the most suppressed swing-and-miss environments for breaking balls in Major League Baseball. Similar to the connection between the two Los Angeles ballparks, I wonder if environmental factors such as weather-related effects are a primary contributor to this phenomenon given that both parks are located in the Washington-Baltimore combined statistical area. Similar to the list of fastball whiff rate laggards, Chase Field and Busch Stadium rank as two of the lowest swing-and-miss environments for breaking balls.
Off-Speed
As mentioned earlier, I have classified changeups and splitters as off-speed pitches for the following analysis. Let’s take a look at the ballparks that had the highest off-speed whiff rates from 2021 to 2023:
As shown by the table above, Angel Stadium of Anaheim is the best ballpark in baseball at generating swing-and-miss on off-speed pitches by a considerable margin, with a 37.0% whiff rate on off-speed pitches from 2021 to 2023. loanDepot Park also appears on this leaderboard, displaying how the ballpark is an excellent environment for pitchers to utilize their secondary pitches. Two ballparks that are on top of the strikeout park factor leaderboard, Yankee Stadium, and Tropicana Field, also appear on this leaderboard. Perhaps the batter’s eye located over Monument Park in center field creates perception issues for opposing hitters when facing off-speed pitches.
Coors Field once again appears among the most suppressed swing-and-miss environments in all of baseball, with off-speed pitches generating a 27.5% whiff rate at the park from 2021 to 2023. This indicates that pitchers at Coors Field are better off using their breaking balls as opposed to fastballs and off-speed pitches if they intend to generate swing-and-miss against opposing hitters. Nationals Park ranks as one of the worst ballparks to utilize any secondary pitches in, with the park displaying the most suppressed swing-and-miss environments for off-speed pitches from 2021 to 2023.
Implications
Before discussing the implications of this research, it is important to acknowledge the limitations of this analysis. The whiff rates for each ballpark as grouped by pitch classification are not weighed or adjusted in any matter and are simply grouped based on the home ballpark in which each event took place. While I believe that analyzing three seasons of data provides a large enough sample size to account for such a factor, the quality of the hitting team and pitching team might have some influence on these results. For example, given the St. Louis Cardinals‘ recent focus on ground ball pitchers, it is possible that the low whiff rates at Busch Stadium on fastballs and breaking balls were caused by organizational philosophy rather than any park factor.
Overall, I believe the results of this research are intriguing and can open up a couple of avenues for future research. It may have been noticed that I have not analyzed the elevated strikeout environment at Truist Park so far in this article. This is because I find the strikeout park factor of Truist Park particularly interesting, as it might provide some valuable insight into what factors determine whether a park is strikeout-friendly or not.
Referring back to the strikeout park factor leaderboard, Truist Park is one of the biggest surprises among the top five highest strikeout environments given the fact that it is an open-air stadium, not a retractable roof or fixed dome. In addition to being one of the highest strikeout environments in baseball, Truist Park creates the 5th most swing-and-miss against fastballs and the most amount of swing-and-miss against breaking balls by a considerable margin. One of the significant features of Truist Park is The Battery mixed-use development located around the ballpark, and I wonder if this development plays a role in the ballpark’s elevated strikeout environment. Perhaps the buildings surrounding the park were aligned in such a way that creates wind patterns and atmospheric conditions that are more favorable to generating swing-and-miss? This ties back to the theories I presented on how the environments of the Greater Los Angeles and Washington-Baltimore areas might have an impact on breaking ball effectiveness. This theory could also explain why Yankee Stadium is also an elevated strikeout environment, as the stadium is neighbored by city buildings in the outfield which could alter wind patterns and other atmospheric conditions. Further analysis of this hypothesis would require someone with a deeper understanding of science and meteorology than I do but it is one of the best theories that I can come up with as to why the park generates so much swing-and-miss on breaking balls.
Or perhaps the Braves are just really good at throwing breaking balls.
This analysis can be used to identify streamers in fantasy baseball. If a pitcher throws a lot of non-fastballs, perhaps it is not a good idea to start them when they are pitching at Nationals Park where the swing-and-miss environment on these pitches is suppressed. If a pitcher throws a lot of fastballs, then maybe it is a good idea to start them when they are pitching at T-Mobile Park where the swing-and-miss environment on these pitches is elevated. In conclusion, analyzing whiff rates by ballpark can provide valuable insight into how certain environments can benefit certain pitchers, and opens up more avenues of research into the effects that park factors have on in-game performance.
Photos from Wikimedia Commons | Featured Image by Justin Redler (@reldernitsuj on Twitter)