![]() ![]() Here’s an interesting observation - batters have appeared to hit balls at larger launch angles - this is most clear for sliders, curve balls, and change ups. What about launch angles? Below I display boxplots of launch angles for all pitch types and seasons. The basic message I get from this graph is that the exit velocities on balls in play haven’t changed much from 2015 to 2017. (In other words, the batter may be more likely to hit a ground ball or a pop up.) First I show boxplots of the exit velocities for each pitch type and season. If the batter is not getting good wood on the ball (say, if he was fooled by the pitch), then that would result in a lower exit velocity and a less-than-optimal launch angle. ![]() (Of course, as one would expect, miss rates for off-speed pitches are greater than the miss rates for fastballs.)Īnother measure of pitching effective is the quality of the balls that come off of the bat. Arrieta’ miss rate for a changeup increased in 2017, but he had lower miss rates for his sinkers and four-seamers. Below I have displayed these miss rates for all pitch types and all seasons. One measure of pitching effectiveness is the fraction of swung pitches that are missed by the batter. (Here I’m using the function in the cowplot package that allows one to combine ggplot2 objects in a single graph.) The obvious conclusion is that Arrieta is not throwing these pitches in 2017 as he was in the 2015 season. Also the movement of his other pitches also shows changes to larger pfx_x values. I notice significant changes in the horizontal movement of his four-seamer and curve ball in 2017. Since movement is an important component of a pitch, let’s explore the horizontal and vertical movements of these pitches for the three seasons. (By the way, I illustrate the cowplot package’s capability to insert a graphic on a ggplot2 figure.) Even his curve ball tended to be thrown at a smaller speed in 2017. But this decrease in speed carries over to all of his pitches. This demonstrates that the average speed in his four-seamer has dropped a few mph from 2015 to 2017. Below I display boxplots of the release speeds for each of the pitches, comparing the three seasons. The concern about Arrieta was on the decrease in his fastball speed. In contrast, in 2017, he seemed to rely on sinkers and fewer sliders and four-seamers. In 2015, he appeared to throw a high number of sinkers and sliders and a good fraction of four-seamers. He throws five pitches, a changeup (CH), a curve ball (CU), a four-seam fastball (FF), a sinker (SI), and a slider (SL), but as the graph indicates, the distribution of these pitches has changed from 2015 to 2017. What Pitches Does Jake Throw?įirst let’s explore Arrieta’s pitch types. ![]() I’m using Statcast data for the 2015 through 2017 seasons. (You’ll see the graphs below plotted using the default theme provided by this package.). How has Arrieta’s pitching effectiveness changed from 2015 to 2017?Īs a side point, I’ll be trying out the cowplot package that provides some add-ons to the ggplot2 graphing package.What about the movement of these pitches?.Do we see a decrease in speed in his pitches over the last three seasons?.This discussion motivated some questions to explore: He spent much of the hot stove season unsigned as a free agent and the story was that many teams were reluctant to give him a long-term contract due to his decreased fastball velocity. He won the NL Cy Young award in 2015, but his performance has declined the last two seasons. They were desperately looking for a veteran to solidify the starting rotation and it appears that Arrieta will fit the bill. As a Phillies fan, I’m obviously excited that Jake Arrieta is now on the Phillies pitching staff. ![]()
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