MLB Batting Statistics By Year

The following analysis was performed using the following dataset from Baseball-Reference.com

Major League Batting Year-by-Year Averages | Baseball-Reference.com

Evaluating whether MLB offense has increased since the start of the Live Ball Era in 1920 involves looking at various offensive statistics over a century of baseball history. The Live Ball Era marked a significant shift in the style of play, moving away from the Dead Ball Era where low-scoring games dominated. Key factors contributing to this shift included changes in the ball’s construction, rule changes, and changes in player strategies and equipment.

Some of the key offensive metrics to consider when assessing changes in offense include:

  1. Batting Average (BA): The rate at which batters successfully hit the ball and reach base safely.
  2. Runs Scored (R): Total runs scored by a team, an indicator of overall offensive production.
  3. Home Runs (HR): The Live Ball Era saw a substantial increase in home runs, highlighted by players like Babe Ruth setting new records for home runs.
  4. Slugging Percentage (SLG): A measure of the power of a hitter, calculated as total bases divided by at-bats.
  5. On-Base Percentage (OBP): How often a batter reaches base, combining hits, walks, and hit-by-pitches.
  6. Runs per Game (R/G): Average runs scored per game, giving an overall sense of the game’s offensive environment.

Overall, the Live Ball Era has been characterized by an increase in these offensive statistics, reflecting a shift towards a more dynamic and powerful style of play. The trend in offensive production isn’t linear, as various factors such as rule changes, pitcher strategies, ballpark dimensions, and player training have influenced these statistics over time. Periods like the Steroid Era in the late 1990s and early 2000s also saw a significant surge in offensive numbers, particularly in home runs.

To provide a more detailed analysis, one would ideally examine historical data from MLB seasons since 1920, charting the trends in these key offensive metrics. This would give a clearer picture of how MLB offense has evolved throughout the Live Ball Era.


Let’s examine different batting metrics starting from the beginning of the Live Ball Era to identify any emerging trends.

First, let’s look at the average runs per game since the inception of the Live Ball Era. Surprisingly the average runs per game have slightly decreases since 1920. A correlation of -0.22 does not indicate a strong indicator of change, and there is one outlier in 1968 where the average was 3.42. The year with the greatest average runs per game is in 1930 at 5.49 runs per game, which we will also look at. Removing these two data points would certainly decrease the Pearson Correlation factor.

Average Runs Per Game

The year 1968 in Major League Baseball is famously known as The Year of the Pitcher due to its record low runs per game, and several factors contributed to this phenomenon:

  1. Dominant Pitching Performances: This era featured some of the greatest pitchers in baseball history, like Bob Gibson, Denny McLain, and Don Drysdale. They delivered exceptional performances throughout the season. For instance, Bob Gibson had an ERA (Earned Run Average) of 1.12 for the season, a modern-era record.
  2. Raised Pitcher’s Mound: During this period, the pitcher’s mound was higher than it is today, which gave pitchers a significant advantage over hitters. The elevated mound allowed pitchers to generate more downward force on their pitches, making them harder to hit.
  3. Larger Strike Zone: The strike zone was interpreted more generously for pitchers at this time, extending from the knees to the armpits. A larger strike zone meant batters had a more challenging time controlling the strike zone and getting hits.
  4. Lack of Lively Ball: The ball used in MLB at that time was not as lively as in other eras, particularly compared to the balls used in later decades. This made it more difficult for hitters to generate power and hit home runs.
  5. Hitter’s Approach and Equipment: Hitters’ approaches and the equipment available at the time were not as advanced as in later years. Training techniques, batting analytics, and equipment that later helped hitters improve were not yet developed.

The combination of these factors led to a significant decline in offensive output, making 1968 one of the most pitcher-dominated seasons in MLB history. The extreme nature of this pitching dominance led to rule changes in 1969, including lowering the pitcher’s mound and shrinking the strike zone, to restore a more balanced dynamic between pitching and hitting.

The year 1930 in Major League Baseball is known for its remarkably high offensive output, and several factors contributed to this surge in runs scored:

  1. Lively Ball Era: The 1930 season was in the midst of the Lively Ball Era, which began in the 1920s. This era was characterized by significant changes in the baseball itself, making it bouncier and easier to hit for distance.
  2. Hitting Technique and Philosophy: Hitting techniques and philosophies continued to evolve during this time. Batters were increasingly focusing on power and run production, influenced by players like Babe Ruth, who revolutionized the game with his home run hitting approach.
  3. Quality of Pitching: Some historians suggest that the quality of pitching was not as strong during this period. The expansion of the league and the high demand for pitchers may have diluted the talent pool, leading to less effective pitching.
  4. Ballpark Factors: Ballpark dimensions and conditions in that era often favored hitters. Many ballparks had shorter fences or were designed in a way that made it easier to hit home runs and extra-base hits.
  5. Economic Factors: The Great Depression, which began in 1929, led to cost-cutting measures in many aspects of the game, including the maintenance of baseballs. This might have resulted in the use of worn, softer balls that were easier to hit.
  6. Rule Changes and Enforcement: There were fewer rules restricting offensive strategies, and rules against things like spitballs (which had been banned but were still occasionally used) were not as strictly enforced.

The combination of these factors created an environment where hitters could thrive, leading to the high-scoring games of the 1930 season. It’s often considered one of the most hitter-friendly seasons in MLB history.


Reviewing batting average by year, we see a stronger downward Pearson Correlation at -0.57. This indicates a moderate negative relationship between time and batting average, suggesting that batting averages have generally declined over the years.

Batting Average

A few key factors might explain this trend:

  1. Improved Pitching Techniques and Training: Over the years, pitchers have developed more sophisticated techniques, such as mastering multiple types of pitches and increasing velocity. Additionally, advancements in training methods and analytics have contributed to more effective pitching strategies.
  2. Increased Emphasis on Power Hitting: Modern baseball has seen a shift in focus towards power hitting, emphasizing home runs and extra-base hits. This approach often comes with a higher strikeout rate and lower batting averages, as hitters are willing to sacrifice average for power.
  3. Defensive Shifts and Advanced Analytics: The use of advanced analytics in defensive positioning, such as the shift, has become more prevalent. Teams strategically position fielders based on a batter’s hitting tendencies, leading to more outs and lower batting averages.
  4. Quality of Pitching Talent: The overall quality and depth of pitching talent have increased, with more specialized roles such as middle relievers, setup men, and closers. This means batters are often facing fresher, more effective pitchers throughout the game.
  5. Changes in Ballpark Dimensions and Conditions: Over the years, changes in ballpark dimensions and playing conditions have also played a role. Some modern parks are designed to be more pitcher-friendly, which can affect batting averages.
  6. Rule Changes and Enforcement: Various rule changes and stricter enforcement, such as the crackdown on performance-enhancing drugs, have also influenced batting performance.

The correlation coefficient of -0.57, while not indicative of an extremely strong relationship, is significant enough to suggest a real, moderate trend of decreasing batting averages over the years in Major League Baseball. This trend reflects the evolving nature of the game, where different skills and strategies gain prominence in different eras.

Next let’s review average home runs per game. It’s widely known that baseball teams have implement a more power hitting strategy over the past several decades, and looking at the following scatter plot we see a Pearson Correlation of 0.87, which suggests a strong correlation.

Factors such as the Steroid Era in baseball has contributed to the increase in power hitting.

Average Home Runs


We can also see this trend in the average number of doubles per game. Although the correlation is not as strong, with a correlation coefficient of 0.36, the graph depicting this data reveals an intriguing pattern of fluctuations in doubles hit per game since 1920.

Average Doubles


Overall hits per year have declined over the years, with a correlation coefficient of -0.54, indicating a moderate negative relationship between time and the total number of hits. This trend aligns with the strategic shift in baseball towards power hitting, emphasizing home runs and doubles, as opposed to the traditional small ball approach.

Average Hits


Slugging percentage, indeed, serves as an effective indicator of power in baseball, as it measures the average number of bases a player earns per at-bat. With a correlation coefficient of 0.46, there is a moderate positive relationship indicating an overall increase in slugging percentage over the years. However, the scattered nature of the plot points suggests variability in this trend, with notable growth observed beginning with the Steroid Era in the 1980s.

Average Slugging Percentage

The observation of a strong Pearson Correlation of 0.96 in average strikeouts per game is a compelling indicator of the shift towards power hitting in baseball. This high correlation suggests a very strong positive relationship, indicating that strikeouts have significantly increased over the years. The consistency of this trend, with very little fluctuation, shows baseball teams acceptance of strikeouts as a trade-off for the potential of increased power at the plate.

Average Strike Outs


The analysis of average stolen bases per game reveals insightful trends about the evolving strategies in baseball, particularly in the context of the shift towards power hitting. Power hitters often have limited speed, and this is reflected in the patterns of stolen base statistics.

Average Stolen Bases

Conclusion
Despite a marginal decline in runs per game since the start of the Live Ball Era, there have been substantial shifts in offensive tactics and results in Major League Baseball since 1920. The primary insights from this analysis highlight:

  1. Decrease in Batting Averages: There’s a moderate negative relationship between time and batting average since 1920, indicated by a Pearson Correlation of -0.57. This suggests a general decline in batting averages over the years, likely due to improved pitching techniques, an increased emphasis on power hitting, the use of defensive shifts, and other factors.
  2. Shift Towards Power Hitting: The strategic focus in baseball has shifted towards power hitting, as evidenced by increases in home runs and slugging percentages, particularly during the Steroid Era in the 1980s and 1990s. This shift is further supported by a strong positive correlation (0.87) in average home runs per game.
  3. Increase in Strikeouts: With a Pearson Correlation of 0.96, there’s a very strong positive relationship between time and average strikeouts per game, indicating a significant increase in strikeouts. This trend aligns with the acceptance of strikeouts as a trade-off for the potential of increased power at the plate.
  4. Variability in Doubles: While there’s a positive correlation in the average number of doubles per game, the trend is not as strong and shows considerable fluctuations over time.
  5. Decline in Overall Hits and Stolen Bases: There’s a moderate negative relationship between time and the total number of hits, as well as a decline in stolen bases per game. This reflects the diminished emphasis on traditional small ball tactics in favor of power hitting strategies.
  6. Historical Context: Specific years like 1968 (The Year of the Pitcher) and 1930 (a peak offensive year) are highlighted to show how various factors such as pitcher dominance, changes in ball construction, and economic conditions have uniquely influenced the game in different eras.

Overall, these trends reflect a fundamental shift in the nature of MLB play, moving away from a focus on hitting for average and speed-based strategies to an era dominated by power hitting and home run-centric offenses. This evolution has been shaped by advancements in player training, analytics, changes in rules and equipment, and broader strategic adjustments within the game.