One of the greatest philosophers of our time in Marilyn Monroe once said that diamonds are a girl's best friend. The same principle applies to pitchers and fastballs.
There is really nothing better in baseball when a starter or a reliever opts for a 95 mph four-seam pitch to get a crucial out in a tight ball game. While the focus in pitcher development has been on spin rates and improved breaking pitches, we want this article to be centered on the heater and remind everyone that it is still an effective option.
We will go about this endeavor by focusing on vertical movement on a four-seam fastball. We split this into two categories. The first is how it is generated by drawing correlations between velocity and spin rate. The second is to determine the effectiveness of four-seam movement, in the context of Whiff% and PutAway%, which are both Statcast metrics. This will be conducted through regressions to see if a formal correlation does exist.
Now that we have set the table, let's eat:
Vertical Movement Generation
As a refresher, vertical movement refers to inches of drop for any pitch. With the focus on four-seam fastballs, along with reference to Figure One below, we compiled a sample of starting pitchers who pitched at least 100 innings and threw at least 100 heaters. This resulted in 104 qualified arms. As one can see, the results are favorable:
With an r-squared of 0.3376, there appears to be some correlation between vertical movement being derived from velocity. Also notice that as we move down the regression line, the harder a starter throws, there is a reduction in vertical movement. This should make sense, as the goal of any fastball is for it to move in a linear line.
Because gravity exists, it will drop vertically. However, if a starter adds an extra four to five mph in velocity, this will limit that decline.
Now let's turn to spin rate. In accordance with Figure Two, the correlation is not as strong:
While an r-squared of 0.1135 is low, I would like to present the following thought experiment. If the coefficient was substantially lower, such as 0.0006 for example, we wold not talk about it in this post.
The fact that correlation was discernible is admittedly fascinating. Overall, four-seam spin rate does not have the greatest impact on vertical movement, but it may be something to dive into for further analysis.
Vertical Movement Effectiveness
We now pivot to effectiveness. Vertical movement on four-seamers, and even on other pitch types, can be effective in deceiving opposing batters. With our focus on fastballs, we use the same sample above for our breakdown, focusing on correlations between Whiff% and PutAway% with this movement type.
Our results for Whiff% are shown below in Figure Three:
While the r-squared does not fall in that broad range of 0.30 and 0.60 for statistical significance, there can be some level of correlation drawn between a starting pitcher's swing-and-miss rate and the vertical movement of their four-seam heater. With a majority of starters in this study, as this movement is consistent or decreasing, a pitcher's Whiff% may increase.
In the context of PutAway%, the correlation is less than that of Whiff%, but one still exists:
With an r-squared of 0.1323, as shown in Figure Four above, there is some existing correlation, although it is not a strong one. While a four-seam pitch does not present the desirable movement of a breaking pitch, there is some trend in deception with it's vertical movement, something that we did not initially predict.
Recommendation
Here's what starting pitchers should do to improve their four-seam fastball. Place an emphasis on velocity instead of spin rate. When that component is low, vertical movement also decreases. As a result, of movement being low, this may increase the probability of an offensive player either swinging through and missing or being put away with a strikeout.
If this is accomplished, a fastball can truly become a pitcher's best friend.
Thank you so much for choosing The Launch Angle for some out-of-the-box baseball analysis! If you liked this post, click on this link for our previous article.
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