Analysis

Yet Another Version of Charlie Morton is Dominating Baseball

A brief glance at the pitching WAR leaderboard illustrates just how strange a season 2019 has been with regards to pitcher success.

From FanGraphs.com

If these are the ten pitchers you predicted to be the best in baseball this season, then you were either pulling names out of a hat and got extremely lucky or are somehow simultaneously a relative of Lucas Giolito, Matt Boyd, Hyun-Jin Ryu, Lance Lynn, Charlie Morton, and Mike Minor. All of the aforementioned surprises on this list deserve an article of their own (and if you would like to read about Giolito, allow me to recommend this piece by Mike Petriello), but in this article, I’d like to a take a look at how Charlie Morton has achieved his early season success. As the image above notes, his 2.3 fWAR ranks 8th in the league and his 30.4 K% ranks tenth among all qualified starters and would be the highest season mark of his career if the season ended today.

You might remember, however, that this is not the type of pitcher Morton has always been. His career was revitalized in 2017 after the Astros, who were intrigued by Morton’s 1.4 MPH increase in his average sinker velocity from 2015 to 2016 (despite only pitching 17.1 major-league innings in 2016), signed him a two-year, 14-million dollar deal. Prior to ending up in Houston, Morton profiled as the type of pitcher for which Pittsburgh had become famous throughout their success: an extreme ground-ball pitcher who was more focused on generating weak contact than swings and misses. In 2015, his last season with Pittsburgh, he posted the highest ground-ball rate of his career at 57.3%, while also possessing meager 17.1% strikeout rate. This resulted in a mediocre 4.69 ERA in 129 innings just three years before he would put up a 3.13 ERA in 167 innings alongside a 28.9% strikeout percentage in 2018.

So, how exactly did the Astros turn a ground-ball pitcher whose strikeout skill was well-below league average into one of the better starters in baseball? In short, they convinced him to throw a four-seam fastball, which benefited from a velocity increase from 92.8 to 95.7 MPH after joining Houston, more often than his sinker and to locate that four-seamer up in the strike zone. Below is a heatmap of where Morton was throwing his fastballs (both his four-seam and sinker) in 2015 and 2018, illustrating the change. First in 2015:

From FanGraphs.com

And now, 2018. Note the increase in percentage of pitches thrown in the upper-third of the strike zone, coupled with an slight decrease in the percentage of pitches thrown at the very bottom of the strike-zone.

From FanGraphs.com

The result of this change was a massive increase in swing and miss percentage on both his four-seamer and his sinker. In 2015, hitters swung through a Morton fastball only 10.9 percent of the time it was thrown, while in 2018, they missed 21.7 percent of the reinvented pitcher’s fastballs. Add on to this the fact that he threw his four-seam fastball much more often when with the Astros (31.1 percent in 2018 compared to 6.4 percent in 2015) and it is easy to see where the strikeouts came from after the right-hander’s move to Houston.

The new hard-throwing version of Charlie Morton put up 3.1 and 2.9 wins above replacement in 2017 and 2018 respectively, making his dominance in 2019 seem a bit less unexpected, and yet it is another change in pitch mix that has fueled Morton’s success two months into the season. I created the table below that illustrates Morton’s pitch mix in 2015, 2018, and 2019 along with the wOBA allowed for each pitch in its respective season. You might notice that his pitch mix numbers don’t add up to exactly 100 percent which is because I left out Morton’s cutter and split finger fastballs for these seasons as he throws them far less often than his sinker, four-seam fastball, and curveball.

Data Courtesy of Baseball Savant

In 2019, Morton has transitioned into a curveball-first starter, à la Rich Hill, and the result has been the most dominant half-season in his career. In each of the seasons listed above, Morton’s curveball was his best pitch according to wOBA allowed and perhaps this simple observation contributed to the Rays interest in Morton, seeing this pitch-mix change as room for even more improvement. Another explanation for Morton’s declining dependence on his fastball is the fact that the average velocity on his fastballs (both four-seam and sinkers) is much lower than it was in 2018, dropping from 94.9 MPH to 92.5 MPH. The best major-leaguers are adaptable and it could be the case that Morton, having noticed this decrease in his fastball’s velocity, turned to his curveball to make up for his less effective fastball.

We should take a moment to admire just how nasty Morton’s curveball is. Using Statcast’s new pitch movement metrics, we can say that Morton’s curveball has the second most horizontal movement among all major league curveballs, behind only Ryan Pressly, who just broke the record for consecutive appearances without allowing a run. Just look at how nasty this pitch is.

The horizontal break has on Morton’s curveball has been improving every year since he joined the Astros in 2017 and 2019 is no exception. It may very well be possible that Morton’s curve is only getting better which could help explain how his opposing hitter’s .137 wOBA against the pitch is easily the lowest in his career and one of the best marks for any pitch in the league.

With aging curves seemingly back to normal after the steroid era, Morton has defied conventional wisdom by constantly making adjustments into his mid-30’s in order to have the best years of his career. As the graph above illustrates, since joining the Astros in 2017, he has seen a steady decline in expected weighted on-base-average (a metric which measures quality of contact) each season. The graph’s linear decline can be a bit a misleading however, as Morton’s rise to being one of the best pitchers in the game has been anything but linear, with frequent, large adjustments being the key to the 35-year-old pitcher’s dominance.

Featured Image: Keith Allison, Flickr

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Eric Albers

Recent graduate of Temple University with a degree in Mathematics and soon-to-be Ph.D. student at the University of Illinois at Chicago. Most of my time not spent reading/writing/thinking about Mathematics is spent reading/writing/thinking about Baseball. Here on Diamond Digest I write primarily about the Mets and Rays.

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