MLB: Debunking the juiced baseball theory of 2017

PORT ST. LUCIE, FL - MARCH 7: Major League Baseballs lie in a bag during MLB Spring Training at a game between the Atlanta Braves and the New York Mets on March 7, 2005 at Tradition Field in Port St. Lucie, Florida. (Photo by Ronald Martinez/Getty Images)
PORT ST. LUCIE, FL - MARCH 7: Major League Baseballs lie in a bag during MLB Spring Training at a game between the Atlanta Braves and the New York Mets on March 7, 2005 at Tradition Field in Port St. Lucie, Florida. (Photo by Ronald Martinez/Getty Images) /

The MLB had a record number of homeruns and many were claiming the baseball was juiced, I say that is false and here is why.

There have been lots of rumors swirling from MLB players, coaches, and organizations regarding the idea that baseballs have been flying further in 2017, but do the statistics agree with their claim?

When tackling this theory, I thought the first place to look is that pitchers are throwing harder.

Here’s what I found regarding pitchers velocities:

Since 2002, the farthest the data set from Fangraphs, and I have put into a graph, is that there has been a dramatic increase in pitch speed. In 2002, the average fastball velocity for all pitchers was just 89.0 MPH, while in 2017, the average fastball velocity for all pitchers increase 3.8 MPH to 92.8 MPH. Relief pitchers have had an even more dramatic increase. In 2002, the average fastball velocity was 89.8 MPH, and by 2017, the average fastball velocity increased to 93.7 MPH.

Initially, this spawned the idea that this has to be the reason for the ball flying further. The old saying goes, “The harder they throw it the farther it goes.” However, doing a little more in depth research, and a short video from John Brenkus with Sports Science, that saying is not as correct as one would think. The link is embedded if you would like to see.

Here is percent increase in pitch velocity alongside the added distance to baseballs with the added velocities:

Clearly, baseballs only added a couple of feet from the added pitch velocity. With the distance being so small, if the “Juiced Baseball” theory is to be true, that is not enough evidence.

After realizing pitchers were not the full story, the idea came that, would them throwing harder not make the ball more difficult to hit? I mean, anyone who has played baseball has realized the harder the pitch, the more difficult to hit to be true. As Pete Rose says, “It’s a round bat and a round ball, and you got to hit it square.”

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This is exactly what I found via strikeout rates. If you have not heard, baseball players have also been striking out at record rates alongside more homeruns. In 2002, the average strikeouts per game was 6.47. For 2016 and 2017, we have seen 8.03 and 8.25 strikeouts per game. This is also almost double that of the historical average. Thus, supporting the idea that faster thrown baseballs are tougher to hit.

Even more interesting than strikeouts there has been another interesting thing going on in baseball.

The type of contact players are making on pitches has had a unique trend:

The orange line is what statisticians call “Medium” contact on the baseball. There are certain criteria regarding hit velocity, hang time, etc. That has been on a steady decline, seemingly on pace with the increase in pitch velocity, further supporting that baseballs are harder to hit when thrown harder.

However, look at the grey and blue lines. The grey line is the “Hard” contact on the baseball. Why is it going up? I mean the blue line, “Soft” contact on the baseball one would expect that to increase with increase in velocity, but why is the “Hard” contact?

This is where my theory is going to come in, and that is that players are swinging for the fences. The only argument that would go against this is that the average batted balls in play are going faster of the bat taking away from the “Medium” contact type and adding to the “High” contact type. However, I can debunk that as well with Statcast:

For reference to my tables: FB = Fly ball, GB = Ground Ball, and Players > 90 MPH references the number of players finishing the season with average exit velocities over 90 MPH. 

If anything is going on it is a dead baseball problem. There were 70 less players to average 90 MPH of exit velocities off the bat this past season compared to 2016. Incredibly, 2017 also saw a drop in average MPH off the bat.

Even so, to further support my theory of batters swinging for the fence, look at the drop of Average and Median Ground Ball Velocities. They dropped significantly, by nearly 3 MPH. This tells me even more that players are either getting all or nothing.

“Medium” Contact rates on baseballs are going down, “Hard” Contact rates are going up, and strikeouts are increasing evenly with homeruns. Everything checks out with my theory of guys are just swinging for the fence. Clearly the balls are not getting hit harder.

So how are they getting hit over the fence at a higher rate? Launch Angles.

I have two points of evidence supporting better launch angles. One is this graph regarding flyball, groundball, and line drive rates and the other is another Sports Science video.

As you can see, the Line Drive rate and the Fly Ball rate took a massive dip from 2010 to 2012. Well, so too did the homerun rate. Now look at the years of 2015 to 2017, practically rebounded back to the end of the steroid era.

My theory on this, players have begun to perfect the launch angle, and they are going for it knowing if the get in the certain range swinging hard, its going to go over the fence. If pitchers are pumping more heat in terms of velocity, they adjusted to swinging at different launch angles, fighting power with power. If you do not believe me and the correlation, even if it is slight, check out Baseball-References season by season homerun rates.

My second point, as mentioned, is another Sports Science video this time breaking down Cody Bellinger’s swing. If you recall from the first video, they mentioned Nomar Garciaparra and if he adjusted his launch angle from 10 degrees to 20 degrees, all things being equal, he would gain an incredible 15 feet of distance! The breakdown of Bellinger was even more dramatic. He has an average homerun launch angle of 27 degrees, and if he decreased that to 20 degrees, he would lose 30 feet of distance!

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In conclusion, 2017 saw more homeruns not because of juiced baseballs, but players got better at their adjustment to faster pitchers by swinging for the fence and hitting the ball at better launch angles, even if they are striking out at never-before-seen rates.