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  • Writer's pictureBruin Sports Analytics

Refs Vs. Teams: How Have Penalties Changed the NFL Over the Years?

By: Atij Mahesh



Over the years in the NFL, penalties have shaped the game tremendously. Whether determining playoff seeding, game outcomes, or fines, players and franchise fans suffer from the curse of player penalization. Although always part of the game, many argue that penalties have increased recently, especially those favoring offensive games. This article delves into the evolution of penalties within the NFL, tracking their increase or decrease over time to understand their impact on the sport. We'll explore which penalties have significantly affected game outcomes and analyze trends to see which infractions have become more or less common. Through this examination, we aim to shed light on how the rules and their enforcement have shifted, influencing the game's strategic complexity and the balance between offense and defense.


Using all penalty data from the NFL from the 2000 to the 2023 season, I first filtered out the most prevalent penalties across the years. I also chose to focus on the penalties that occurred at least 0.2 times/game (at least once every 5 games) to exclude odd, rare penalties that infrequently occur throughout the years. After this, I only included the penalties with at least 3 data points (so they have a discernible trend over the years). After cleaning the data, we are left analyzing the following 18 penalties: False Start, Offensive Holding, Defensive Pass Interference, Defensive Offside, Defensive Holding, Delay of Game, Unnecessary Roughness, Encroachment, Illegal Use of Hands, Illegal Block Above the Waist, Roughing the Passer, Face Mask (15 Yards), Offensive Pass Interference, Illegal Contact, Personal Foul, Illegal Formation, Unsportsmanlike Conduct, and Neutral Zone Infraction.


Analyzing trends in offensive penalties within the NFL reveals patterns and shifts over the years. The frequency of false starts has notably decreased, indicating possibly better discipline or adjustments in offensive line tactics. 



Conversely, offensive holding penalties have seen a slight increase overall, despite experiencing a drop from 2020 to 2023, suggesting a fluctuation in the enforcement of this rule or changes in offensive line playcalling.



The illegal block above the waist has shown no clear trend, with only two standout years in 2005 and 2018 marking significant occurrences. Offensive pass interference presented a notable spike from 2014 to 2019, followed by a decrease, possibly reflecting a period of adjustment to rule changes or enforcement emphasis by the league before stabilizing. Additionally, delay-of-game penalties have had no discernible trend, and have fluctuated drastically between seasons. Lastly, penalties for illegal formation have remained relatively constant.


The trends in defensive penalties within the NFL offer a window into how defensive strategies and rule enforcement have evolved. Defensive pass interference has shown an overall increase over the years, highlighting a possible response to more aggressive passing games, though there was a noticeable decrease between 2020-2023, possibly due to adjustments in defensive play or rule interpretations. 



Defensive offsides have trended downwards over time, suggesting improved discipline or adjustments in defensive line techniques.



Defensive holding witnessed a significant rise during the 2010s, reflecting tighter enforcement or changes in defensive coverage schemes, followed by a decline in the 2020s, which could indicate an adaptation by defenses to the enforcement trends. Encroachment penalties saw a rapid decrease in the 2010s, becoming quite rare with occurrences of less than 0.2 times per game since 2016, possibly due to better player awareness or changes in how offenses draw defenses offsides. Roughing the passer penalties spiked significantly, indicating a heightened emphasis on quarterback protection, but like other trends, saw a reduction between 2020-2023, which may reflect either a shift in defensive tactics or the impact of recent rule clarifications.



Lastly, neutral zone infractions became more prevalent starting in 2009, steadily increasing over the years and essentially replacing encroachment penalties. This shift underscores an evolving defensive landscape, where the balancing act between aggressive play and penalty avoidance has led to changes in how defenses approach the line of scrimmage. These patterns reveal the nuanced interplay between rule enforcement, player behavior, and team strategy in shaping the defensive aspect of football.


The trends in miscellaneous penalties, such as unnecessary roughness, face mask violations, and unsportsmanlike conduct, reflect broader shifts in the NFL's focus on player safety and sportsmanship. Unnecessary roughness penalties have seen an overall increase over time, reaching a peak in 2015 before experiencing a decline in recent years. This pattern suggests a heightened emphasis on player safety and a subsequent adjustment by players and teams to the league's stricter enforcement, possibly as part of the NFL's broader initiative to reduce dangerous play.



Face mask penalties have been erratic up to 2016, indicating variable enforcement or possibly fluctuating player behavior, but have shown a noticeable decrease in recent years. This decline could be attributed to better coaching, more effective equipment, or players adjusting to the rules, leading to fewer instances of this dangerous infraction. Unsportsmanlike conduct penalties increased up until 2016, which may reflect a period of adjustment to more stringent rules aimed at curbing disrespectful or dangerous behavior on the field. These trends in miscellaneous penalties underscore the NFL's ongoing efforts to protect players and promote a positive sporting environment. The observed decreases in recent years suggest that these efforts are bearing fruit, leading to a safer and more respectful game.




In conclusion, the analysis of penalty trends in the NFL from 2000 to 2023 offers valuable insights into how the game has evolved in response to rule changes, enforcement strategies, and shifts in player behavior. While offensive penalties highlight changes in line tactics and play execution, defensive penalties reflect adjustments to more aggressive passing games and the league's emphasis on protecting quarterbacks. Meanwhile, miscellaneous penalties underline the NFL's commitment to player safety and sportsmanship. Together, these trends illustrate the complex interplay between rules, enforcement, and game strategy, emphasizing the NFL's ongoing efforts to balance competitiveness with safety and fairness. As the league continues to evolve, understanding these penalty trends will remain crucial for teams, players, and fans alike, shaping the future of football.




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