The MLB's 2023 Rule Changes: A First Analysis of Their Impact on the Game
The MLB's 2023 Rule Changes: A First Analysis of Their Impact on the Game
The 2023 Major League Baseball (MLB) season brought about some of the most significant rule changes in recent memory, all designed with the aim of enhancing the pace and quality of play. A 30-second timer between batters and a pitch timer of 15 seconds with bases empty (20 seconds with runners on) were introduced to shorten game times and increase fan engagement. Early reports from Minor League Baseball indicated that these adjustments could reduce the average game duration by nearly 26 minutes. Additionally, the limits on pickoff attempts were anticipated to boost stolen base activity, a prediction supported by the Minor League data, which showed a marked increase in steal attempts and success rates. Furthermore, the bases were enlarged from 15 to 18 inches, a change intended primarily to enhance player safety but expected to have a modest impact on stolen base success rates as well.
Alongside the above, defensive shifts were restricted to ensure a more traditional setup, requiring four infielders to be on the dirt with two on each side of second base. This rule aimed to counteract the decline in the offensive metrics like batting average.
In this article, we will delve into the effects of these rule changes by analyzing key trends before and after their implementation. More than 4,300 matches have been played since the rule changes, and we will explore whether the decline in offensive metrics has been reversed, whether the anticipated rise in stolen base attempts and success rates has materialized, and whether shorter games, combined with the above, have indeed led to increased fan engagement.
Defensive Shifts Ban
“The 2010s will be known as the decade when these defensive shifts exploded in baseball” Matt Kelly for MLB.com.
Defensive shifts in baseball involve repositioning fielders, often stacking them on one side of the field, to better defend against a batter's hitting tendencies. From 2016 to 2022, it became a dominant strategy in MLB, dramatically altering how the game is played.
Analysis of Defensive Shifts Trends (2016-2024)
In 2016, shifts were used in just 17.1% of plate appearances, but by 2022, this figure had more than doubled to 37.5%. Left-handed hitters (LHH) were particularly affected, with shift usage against them soaring from 30.3% in 2016 to 61.8% in 2022, while right-handed hitters (RHH) saw a more modest increase.
In the following sections, we will analyze the effects of shifts on individual players’ performance by comparing wOBA against shifts and non-shifts. Additionally, we will explore the relationship between the league-wide increase in shift percentages and key offensive metrics, aiming to understand why the league ultimately viewed the continued proliferation of shifts as a potential threat to the game's appeal.
Effects of shifts on individual players’ performance
The below line plot illustrates the average wOBA (a version of on-base percentage that accounts for how a player reached base) for both LHH and RHH under shifted and non-shifted defenses over the period from 2016 to 2022.
The analysis of wOBA trends reveals that defensive shifts consistently lowered the offensive performance. For LHH, wOBA under shifted conditions was generally lower than in non-shifted situations, especially from 2016 to 2019, indicating the effectiveness of shifts during this period. Over time, particularly from 2020 onwards, the gap between wOBA with and without shifts narrowed for both LHH and RHH, suggesting that hitters may have adapted to the frequent use of shifts. Despite this, the more significant difference for LHH highlights why (alongside their tendency to pull the ball to the right side) they were more frequently targeted by shifts.
Effects on League-Wide Offensive Metrics before and after 2023
Here, we're examining the trend of major league-wide offensive metrics alongside the rise in defensive shifts and evaluating the impact of the 2023 shift ban on these metrics.
The trends in wOBA, BA, OBP, and SLG from 2016 to 2024 show a clear decline, aligning with the rise in defensive shifts and the analysis in prior sections. Although there was a spike in all metrics in 2023 following the shift ban, by 2024, these metrics had dropped back to almost pre-ban levels. This suggests that while the shift ban initially boosted offense, its long-term impact may be limited, as other factors or adjustments by teams likely offset the intended effects.
Pickoff Limits and Wider Bases
In addition to the defensive shifts ban, the MLB introduced in 2023 limits on pickoff attempts and larger bases to boost stolen base attempts. These changes aimed to make it harder for pitchers to control runners and increase the likelihood of successful steals, creating a faster, more dynamic game that enhances both strategy and fan excitement.
Analysis of Stolen Base Trends (2016-2024)
This time, trends in stolen bases and stolen base attempts per game from 2016 to 2024 clearly reflect the impact of these rule changes. Prior to 2023, both stolen bases and attempts were on a downward trend, indicating a decline in aggressive baserunning strategies. However, with the introduction of the new rules in 2023, there was a sharp increase in both metrics. Stolen bases per game rose significantly, and stolen base attempts per game followed a similar trajectory, highlighting a renewed focus on baserunning as a key offensive strategy.
Additionally, the stolen base success rate saw a noticeable spike following the rule changes. This suggests that the larger bases not only encouraged more attempts but also made stealing more successful. Although there is a slight dip in 2024, the overall success rate remains much higher than in the pre-rule change years, indicating that the effects of the rule changes might have a lasting impact on the game.
Pitch Timer
This rule aimed to reduce the length of games, which had steadily increased over the years, reaching over three hours per game in 2021 and 2022. The goal was to speed up the pace of play, making games more engaging and accessible for fans, both at the stadium and watching from home.
Analysis of Game Duration and Attendance Trends
To evaluate the effectiveness of the pitch timer, we first look at the trend in average game time per nine innings from 1980 to 2024. We can observe this trend using the below line chart to see how game durations have evolved, especially before and after the implementation of the pitch timer in 2023.
The introduction of the pitch timer in 2023 had a significant impact on reducing game duration, with the average time per 9 innings dropping from over 3 hours in 2021 and 2022 to around 2 hours and 36 minutes so far in 2024. This reduction brought the game closer to levels we had not seen since the early 1980s.
We thought it would be also interesting to analyze the trend in attendance, particularly looking at how attendance per game has changed over the years, in conjunction with game times.
The plot shows steady growth in MLB attendance from the 1980s to the early 2000s, followed by fluctuations that stabilized through the early 2010s. A declining trend was observed from 2015 to 2019. The sharp drop in 2020 reflects the COVID-19 pandemic, with a recovery in the following years, though attendance hasn't fully returned to previous highs. While recent rule changes aimed at enhancing the game experience coincide with this period, their direct impact on attendance is difficult to pinpoint, suggesting that broader factors continue to influence fan turnout.
The long-term trend in attendance since 1980 is influenced by population growth and baseball's expansion, making it less reflective of current dynamics. Focusing on data from 2000 onward, however, reveals a different story. The below chart shows a moderate negative correlation (-0.44) between game duration and attendance during recent years, suggesting that longer games are less appealing to modern audiences. This supports MLB's recent efforts to shorten games to boost fan engagement.
In summary, the 2023 MLB rule changes have had a mixed impact on the game. The pitch timer has successfully reduced game durations, aligning them with levels not seen since the 1980s, and this appears to be a positive step in addressing the modern fan’s preference for shorter, more engaging games. The ban on defensive shifts initially boosted offensive metrics, but these gains seem to be leveling off, indicating that teams may be finding new ways to adapt. Meanwhile, the changes to pickoff limits and base sizes have revitalized baserunning strategies, leading to an increase in both stolen base attempts and success rates. While these rule changes have certainly influenced the game, the broader impact on fan engagement, as reflected in attendance figures, remains complex and multifaceted. The continued evolution of the game will reveal whether these changes can sustain long-term interest and excitement in baseball.
Source: MLB, statscast, teamrankings, Baseball-Reference.
Disclaimer: The essence of data analysis is not to capture the entirety of the story but to piece together a narrative from the data fragments at hand. While the data utilized herein is robust and comprehensive, it's not exhaustive. Every statistical representation has its constraints. Our aim is to utilize accessible data judiciously, aiming for an honest and insightful interpretation, recognizing that there are always more layers to the story.