Analysis: The Weird and Wonderful Stuff of Brusdar Graterol
Late last year, unless you were a diehard Minnesota Twins fan, you had likely never heard of Brusdar Graterol. In his time within the Minnesota system, the top prospect had turned some heads with his blazing fastball, but injury concerns and control issues hampered his development and kept him a bit under the radar for most fans. In fact, most people would only learn about Graterol after last season, when he became a major sticking point in the deal to send Mookie Betts to Los Angeles.
In February, when the Red Sox, Dodgers, and Twins were working out the three-team megadeal, Graterol was supposed to go to the Red Sox in return for the Dodgers sending Kenta Maeda to Minnesota. But when the Red Sox balked due to their concerns about his medical records, the Twins and Dodgers reworked the deal amongst themselves and sent Brusdar to LA instead. This generated a lot of news coverage at the time, and it made many people wonder what each team was seeing in Brusdar Graterol. However, once the 2020 season started, it became pretty clear what the Dodgers saw.
Of course, Mookie Betts was the highlight of that trade, and arguably the main reason why the Dodgers have returned to the World Series. But if Mookie was the cake, then Brusdar was the icing on top. At just 21 years old, Graterol showcased some of the most astounding stuff in baseball on the mound. Not only was he effortlessly throwing his fastball over 100 MPH, but those fastballs also had more horizontal movement than his slider (according to Statcast, Graterol’s slider breaks 7 inches on average, while his four seam breaks 9 inches and his sinker breaks 14). As a result, he became a staple of the Dodger bullpen in 2020, putting up a respectable 3.09 ERA, .220 average against, and 1.16 BB/9 in his second big league season.
However, while it can be easy to get caught up in his amazing velocity and movement, the numbers they generate bring about some very confusing trends. See, if I told you there was a pitcher who could throw a 102 MPH fastball with over a foot of break, you would expect him to have one of the highest strikeout rates in the league, right? Well, just take a look at Graterol’s Baseball Savant summary for 2020:
Statistically, Graterol has been one of the single worst pitchers in baseball at avoiding the bat. It’s not a typo: his strikeout rate (5.01 K/9) is in the seventh percentile in MLB, and his whiff rate (swinging strikes/swings) is at the bottom of the barrel. To those who have seen him pitch, these numbers seem so ridiculous as to defy all logic. After all, how could hitters be seeing his fastball well enough to make that much contact? Well, looking into his numbers, there seem to be two major factors at play here: spin and rise.
If you look at the pitchers with the highest strikeout rates in baseball, they usually have two major things in common: incredibly high spin rates and “rising” high-velocity fastballs. Typically, these two things work in lockstep. Basically, the backspin a pitcher puts on his fastball creates an upward force on the ball as it travels to the catcher. If a pitcher can put enough spin on the ball, he can fool the hitter into thinking the ball will drop further than it actually does and get him to swing under it. This is usually true regardless of velocity, but it’s most effective at really high speeds. For the most part, this is why high fastballs are such dangerous weapons for power pitchers with great velocity.
However, if you can’t generate that much spin on the ball, it is a lot harder to generate that effect and get people to swing through your fastball. To illustrate this, let’s compare Graterol with someone who is known for their swing-and-miss stuff: Aroldis Chapman. Now, aside from the fact that Chapman is left handed, he and Graterol seem to be quite similar on the surface. After all, their main repertoire is exactly the same (four-seam, sinker, slider) and both are flame-throwing relievers whose fastballs are regularly clocked at over 100 MPH. However, despite their similarities, Chapman’s strikeout rate is in the 97th percentile in baseball, and he strikes out over 3 times as many hitters compared to Graterol (16.97 K/9 compared to Graterol’s 5.01).
While this may be confusing at first given their similar arsenals and pitching styles, things become much clearer when you look at the spin rates. In 2020, Chapman’s four-seam fastball had an average spin rate of 2,451 RPM. Meanwhile, Graterol’s fastball had an average spin rate of just 2,015 RPM, well below the MLB average of 2,306. As one might expect, this caused a huge difference in where each pitch ends up. In fact, because of the lower spin rate, Graterol’s fastball drops four extra inches on its way to the plate compared to Chapman’s. The result? A 42% whiff rate on Chapman’s four-seam and a 33% whiff rate on his sinker, compared to Graterol’s 20% and 7%(!), respectively.
However, things get even weirder when you start to look into his slider. See, his low strikeout and whiff rates can be largely attributed to how much he throws his sinker (about 2/3 of the time, in fact) and how often it gets hit (again, a whiff rate of 7%). But while he has trouble getting swings and misses on that pitch, he doesn’t have those troubles with his slider. In fact, he posted a 37.8% whiff rate on the pitch in 2020 - a rate that’s better than even Chapman’s (34.8%). Again, spin rates play a key role here. Interestingly, while his fastball spin rates are well below average, the spin on Graterol’s slider is slightly above average (2477 RPM compared to 2439). Now, this is nowhere near an elite spin rate (some pitchers spin their sliders at over 3,000 RPM), but for a pitcher like Graterol that features a 100 MPH fastball, even a breaking ball with an average spin rate can be a dangerous weapon that leaves hitters flailing.
With all of that being said, Graterol has found a way to be very effective on the mound without the help of the strikeout. As I mentioned earlier, Graterol overwhelmingly relies on his sinker, which tends to generate a lot of contact. However, when his sinker does get hit into play, it is almost always beaten into the ground. In 2020, Graterol posted an astounding ground ball rate of 61.5%, good enough for eighth place among relievers this year. It also helps that the movement of his pitches make him really effective at limiting hard contact. In fact, he ranked 17th among relievers this year when it came to hard hit rate. Because of both of these factors, Graterol has also been really good at keeping the ball in the ballpark, allowing just 1 home run throughout the entire 2020 season and postseason.
All in all, Brusdar Graterol has become one of the most fascinating pitchers in baseball - both on the field and in the stat sheet. However, his future brings up a lot of questions. Can he find a way to increase his spin rate over time? Will he be able to improve his strikeout rates? Can he still be effective when his velocity starts to drop later in his career? While these are all interesting questions, we cannot answer any of them for sure right now. Right now, all we can do is enjoy the show as Brusdar and the Dodgers attempt to bring a championship back to LA.