The recent drop in offense in Major League Baseball has been well observed by the industry as shown from the average runs/game dropping from 4.6 to 4.2 from 2002 to 2014. The most notable change has been in the past two seasons where the decrease in runs/game have been .15 (4.32 runs/game in 2012 to 4.17 runs/game in 2013) and .1 runs/game (4.17 in 2013 to 4.07 in 2014) in those two years.
The first place to look in the equation is pitching. During the same time period K% is up over 20% and BB% is down a slightly more than 12.5%. These are not just coincidences as there is high correlation between both runs/game and BB% and runs/game and K%. While notably a small sample is used for this analysis (13 years); the correlations in the chart below shows an R2 (correlation coefficient) of -90% between runs/game and K% and +77% between BB% and runs/game (disproving Brandon Phillips that walks don’t lead to runs but that is for another topic). While the amount of data points may be small, the trend is clear: that pitching continues to improve its dominance over the hitters in Major League Baseball. To evaluate this trend, I evaluated data from FanGraphs on both pitch speed, pitch type and hitter frequencies.
Pitch Speed/Pitch Type
Research presented by Jeff Zimmerman of FanGraphs showed that 25% of pitchers who threw over 100 mph from 2007 to 2013 had Tommy John surgery. And with the increasing epidemic of Tommy John surgery one of the key points as pointed out by Jonah Keri of Grantland in a recent article titled “The Tommy John Epidemic: What’s Behind the Rapid Increase of Pitchers Undergoing Elbow Surgery?” is that as pitchers throw faster, the higher velocity causes higher torque. This puts more pressure on their elbows causing the ulnar collateral ligament to ultimately facture. So just looking at surgery data in general we see that there is an increase in Tommy John surgeries and then the correlation would show and increase in velocity. But just how big is this increase?
To evaluate the change, I looked at the velocities of five different pitches (fastball, slider, cutter, curveball and changeup) over the course of 2002 to 2014 (all of the data available from FanGraphs). From the chart above, the generally increasing slope is apparent with each pitch increase on average by 0.1 to 0.2 MPH per year.
In the chart above, it can be observed that each of these major five pitches have shown a statistically significant increase in speed. This 2% increase seems quite significant as the trend continues to move upwards towards throwing harder and harder. This shows the importance of velocity in the game today. The best way to make a roster is to throw hard, and then the team can hope to teach how to command it. The increased velocity should allow pitchers to induce weaker contact and make them swing and miss more.
Swing and a Miss
As average velocity has increased, hitters will need to make adjustments. Any pitch has two possible results – it is either in the strike zone for a strike or out of the zone for a ball. Prior research has shown that the strike zone is expanding, but the data shows that hitters are also helping to make sure the zone expands. As seen in the chart below, since 2002 hitters have swung at a dramatically higher percentage of pitches out of the zone. At the same time, there has been a dip in the amount of pitches swung at that are actually in the strike zone. These two combined to result in the amount of plate discipline remaining constant, as the overall percentage of pitches swung at has remained around 46.5%.
What is most surprising about the rise in swinging percentage and dominance of pitchers is that there has been a dramatic decrease in pitches overall thrown in the strike zone. With research on pitch framing at a forefront, those extra strikes are vital. Because strikingly enough, the number of pitches thrown inside the strike zone has decreased 18% from 54.6% of pitches to 44.9%. But despite this decrease, the walk rate has dropped while the strike out rate has increased; a result that is quite surprising..
Using data from 2002 to 2014 available on FanGraphs, it is becoming apparent why pitching is so dominant these days with the ever increasing strikeout rate and decreasing walk rates. Pitchers continue to throw harder, allowing them to dominate hitters even if they are not able to effectively hit the strike zone. Hitters are being over-matched with pitches they can’t hit, yet are strangely swinging more at pitches outside of the strike zone than those in the strike zone. This is despite the increase in pitches that would be called balls. Other factors, including fielding and the quality of batted balls, will also impact the results, but overall it is pitchers who are able to dominate in today’s game.
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