By: Matthew Haines
If you’re a hitter, there is one pitch that you like to hit….fastballs. While being the most common pitch in the game today, it is also the easiest pitch to replicate within batting practice. As a result, hitters spend most of their years practicing to hit fastballs.
As pitchers, from their first bullpen, to their last appearance on the mound, the fastball will serve as their primary pitch. No matter the count, no matter the situation, as a pitcher, you are most likely going to throw at least one fastball per at bat while on the mound. (Here’s some stats courtesy of fangraphs to prove it.)
So why does this occur? Hitters are trained from a young age to hit fastballs, and have seen them their whole lives. On the other end, pitchers are constantly trained to throw fastballs to the point of monotony. I am no expert in game theory, but for me, as a pitcher, if I know hitters are more likely to hit fastballs while also more likely to expect a fastball be delivered, why would I throw them one? Some may say velocity; the faster the ball comes in, the harder it is to hit, others may say that throwing a strike is the only thing that matters. However, I wanted to take a deeper dive into this notion. And try to answer the question, should pitcher really be throwing so many fastballs?
First, I want to take a look at fastball trends in the majors throughout the last few years.
As you can see, fastball usage (FB%) has slowly but surely dropped over the last 10 years. Yet, ironically, as presented in my previous article, fastball velocity (FBv) has risen over the last 10 years. So why does this occur? We would assume that as pitchers’ FBs become better and better, FB% would rise, right? I believe this trend’s core lies in my previous statements in the article, in essence, hitters hit fastballs! As more and more data comes to our fingers, analysts are seeing that fastballs are not only the hardest hit balls but also the easiest pitches to track. In result, it is the fastball that results in the most production for a hitter.
To further test the hypothesis that fastballs are indeed hit the hardest and do the most damage, I decided to take a look at which pitch type makes up the largest percentage of barrels. To do so, I took the 7 most common pitches, and looked at 2018 data to determine which pitch type resulted in the most barrels in the MLB.
Clearly, fastballs make up an overwhelming proportion of barrels. However, this is not exactly doing the fastball justice. Therefore, we should not make wild conclusions based off of this clearly, skewed data. Since we know that fastballs made up over half of pitches thrown in 2018, it would be reasonable to assume that they would also make up more than half of barrels in the same year. For this reason, I decided to take a look at what percentage of each pitch resulted in a barrel.
Here we can see, that while the result still remains the same, it is a much smaller difference that originally perceived.
So what can we deduce from this data? Well, that is up to each an every pitcher to make the decision for themselves. However, in knowing that 7.5% of all 4-seam fastballs thrown at the MLB level result in barrels, I would not be surprised to see more and more pitchers, especially those with minus velocity fastballs, continue to shift towards using more off speed and breaking pitches.
It should also be noted that this data is strictly drawn from the MLB, the highest level of competitive baseball. While the data is not currently available, I would venture to say that the percentage of fastball usage in college and high school levels dwarfs the numbers displayed by MLB pitchers. With that being said, I am also comfortable with saying that the metrics on these college/high school fastballs do not come near the levels of their MLB counterparts. For this reason, I believe that an increased use of breaking and offspeed pitches at the college and highschool levels will have an exponentially larger impact on production when compared to the MLB.
Lastly, I want to discuss a bit around the notion of “just throw strikes”. While for most pitchers, their best command is with their fastball and “look the best” when spotting up in bullpens, that does not necessarily mean they will get pitchers the most strikes.
Here we have data showing six common pitch types and their swinging strike percentages (SwStr%). What this shows is, although a pitcher may be more likely to throw their fastball into the zone, that same fastball is also more likely to get hit, or be laid off if it is a ball. As this data shows, the three primary off-speed pitches are almost twice as likely to trigger a swinging strike from the batter. So, while many pitchers may not be able to command their offspeed as well, in many cases, this is made up for by the pitch’s deception of the batter, leading to more swing and misses than an average fastball.
Now that we have shown how useful good offspeed pitches can be, (arguably more useful than a good fastball) I want to reference a bit to the player development side of the game. Specifically, developing breaking balls for young pitchers. There has always been a stigma towards teaching young players how to throw curveballs, sliders, or any other breaking pitch. This stigma is mostly due to the fear of these pitches causing arm injuries in youth pitchers. Up until recently, I had thought much of the same. I was under the impression that supinated and pronated positions in the throwing motion would indeed lead to increased arm injuries in youth pitchers. However, a study by Stephen Lyman, PhD, Glenn S. Fleisig, PhD, James R. Andrews, MD, and E. David Osinski, MA over at the American Sports Medical Institute show quite different findings. In essence, through a study over 14 years tracking youth pitchers, there was little to no evidence to suggest that the use of breaking pitches at a young age lead to an increased risk of arm injury. Since this is an analytics article, I will not go into further detail, but I encourage you all to check out the study itself, or listen to this Eric Cressey podcast, where he and Christian Wonders dive a bit deeper into the subject.
Overall, it is becoming more and more clear that through an increased use of breaking and off-speed pitches, hitters have a harder time barreling off speed and breaking pitches and henceforth, producing for their team. As the data becomes stronger, I would look to see a continued trend towards decreased fastball usage, ultimately leading to an entirely different role for the fastball when used in a pitcher’s arsenal.