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Advanced Analytics: Has the MLB Fly Ball Revolution Hit the High School Level?

Balls are leaving Major League ballparks more often than ever before.The 2017 MLB Home Run rate is up 8% from 2016, putting the league well on pace to surpass the all-time single season Home Run record of 5,693 set in 2000.1
The most prominent theory behind this phenomenon is that players are trying to raise their average launch angle and hit the ball higher. Players are doing this because Home Runs cannot be hit on the ground, and they believe that hitting the ball higher will lead to more Home Runs and a higher Slugging Percentage.
Is a similar trend emerging in amateur baseball as well? Have younger teams begun to hit more Fly Balls, and has that led to a positive impact on their offensive output? We crunched the numbers from over 50,000 High School level baseball teams who used GameChanger to score games over the past three years, and found some interesting trends.2

In order to see whether teams were hitting the ball in the air more often, we calculated the difference in the Fly Ball Percentage (FB%) from 2015 to 2017.3 The results can be seen on the table below:

Change in FB% 2015-2017
Level FB% 2015 FB% 2016 FB% 2017 Percentage Increase 2015-2017
MLB 33.8% 34.6% 35.4% 4.7%
High School 32.5% 32.6% 32.8% 0.9%
According to the data, the “Fly Ball Revolution” has barely begun to take root at the amateur level. The Fly Ball rate has increased just 0.9% over the last two years. Just a fraction of the steady increase in FB% that occurred in Major League Baseball over that span.
However, the slight increase in FB% at the High School baseball level occurred simultaneously with a large increase in the Home Run rate. While the MLB Home Run rate increased 8% from 2016 to 2017, High School level baseball teams saw their Home Run rate grow 9% over that span. In addition, “Fly Ball teams”—a team with a FB% greater than the 2017 median of 32.8%—had a batting average of 0.296, slightly above the 0.291 average put up by “Ground Ball teams”.4
On the surface, the increase in batting average seems to indicate that there is an advantage to hitting more Fly Balls. But, peeling back the layers reveals a much more complicated story. Does hitting more Fly Balls result in more runs scored? The following graph displays the relationship between FB% and Runs per Plate Appearance for High School level baseball teams.
According to the data, a team or player’s ability to hit the ball the air is a poor indicator of their ability to produce runs. This data seems to indicate that focusing on increasing FB% does not necessarily lead to greater offensive output, which is evident by the lack of an obvious positive or negative trend in the data. 
Thus, as we have shown in Advanced Analytics: BABIP - A Quality Statistic Measuring Quality Contact, it may be more important to focus on improving factors such as BABIP or On Base Percentage in order to increase offensive output for a team.
On top of the fact that it appears FB% does not reliably predict Runs, Fly Ball hitting teams at the High School level do not necessarily get more extra base hits than Ground Ball hitting teams. This can be seen by the relationship between FB% and a statistic called Isolated Power (ISO), which measures raw power by calculating the number of extra bases gained by a player or team per At-Bat. The formula for ISO and graph of its relationship with FB% can be seen below:5

ISO = ( 2B + 2*3B + 3*HR ) ÷ AB


A correlation coefficient or R2 value of a graph measures how close the data falls to the regression line (the blue line). The coefficient of 0.029 in the graph above means that just 3% of High School baseball teams’ ISO are affected by their FB%, indicating that it is still a poor performance indicator at the High School level. This is evident by the lack of a cluster of points around the regression line (a correlation coefficient of 1 would have all the points in a straight line on the regression line).

In comparison, the R2 value for the relationship between FB% and ISO in the MLB is 0.325, more than ten times the value for High School level baseball teams. Perhaps the main reason for this differential is that High School level players do not hit Home Runs at a comparable rate to that of MLB players. As of 2017, a Home Run is hit once every 30.3 Plate Appearances in Major League Baseball, while High School teams only hit a Home Run every 212.6 Plate Appearances. The apparent lack of power to hit the ball out of the park at the High School level makes aiming for a higher FB% less advantageous.

Overall, while it looks like amateur players and coaches are beginning to consider applying the Major League mindset of high launch angles to their own hitting strategy, there is minimal evidence to support its efficacy at the High School level. If a player has enough power to hit the ball over the fence at a consistent rate, then focusing on launch angles may be worth it, but those players are usually few and far between. The downsides to attempting to hit the ball in the air can include a higher strikeout rate, more popups, and, most concerningly, potential damage to a player’s batting mechanics. Thus, as with any quick-fix shifts in strategy, coaches should take the Fly Ball Revolution with a grain of salt.

From Michael Model of GameChanger

1  Statistics from ESPN.com

2  Data is from teams composed of players age 13 to 18, over the past three years. Calculated through May 22, 2017

3  MLB data from FanGraphs.com 

4  FB% less than the median

5  From FanGraphs.com 

Baseball, Baseball Stats & Scorekeeping, Advanced Analytics