Modifying Musgrove

The following article was a reader submission by Jason Gindele. You can find his previous articles here, here, and here.

Pirates fans undoubtedly threw their hands in the air after Joe Musgrove threw a no-hitter for the Padres on Friday. Visions of Gerrit Cole, Tyler Glasnow and Charlie Morton flashed through their heads, understandably assuming that Musgrove is the latest ex-Pirate to thrive outside of Pittsburgh. 

As it turns out, the Pirates may have had a hand in Musgrove’s accomplishment. 

Musgrove was a talented-but-underperforming pitcher when the Pirates acquired him in January 2018, finishing the prior year in Houston with a 4.77 ERA and a 4.03 xFIP in 38 games. His numbers were up and down the next two years in Pittsburgh, with a 4.06 ERA and 3.92 xFIP in 2018 and a 4.44 ERA and 4.31 xFIP in 2019. 

Then things changed. He finished the pandemic-shortened 2020 season with a 3.86 ERA and a 3.19 xFIP and there was a new buzz around Musgrove. But the change didn’t just happen when Ben Cherington, Derek Shelton and the rest of the off-field personnel took over in the winter of 2019-20. It started near the end of the 2019 season, while under former pitching coach Ray Searage. 

In this excellent Post-Gazette article, Jason Mackey wrote that Musgrove started keeping his throwing arm closer to his waist in late 2019, allowing him to stay on top of the ball, stick with a more consistent release point and add deception to hitters. In his last five starts of the 2019 season, Musgrove had a 2.89 ERA and 3.28 xFIP. 

Here’s more insight from Musgrove, who recently spoke with David Laurila: “I feel like the change we saw last year was more me just having a really good feel for my delivery, and being able to repeat. I did change my arm-action at the end of 2019. That was [from] watching guys like [Shane] Bieber and [Trevor] Bauer and [Lucas] Giolito, who were a little more consistent with their stuff in the zone than I was. It seemed like they were in really good positions with every pitch, and I’ve always had a good ability to watch somebody move, and be able to repeat that movement myself. I started doing that and saw my numbers jump up, so I went into the offseason and really tried to get more efficient with the arm-path I was taking out of my glove. I think the spin rates and the action on the pitches is kind of something that just comes secondary from that.”

Those mechanical changes conveyed to the 2020 season, under new pitching coach Oscar Marin. But Musgrove also changed his approach, based on conversations with Marin and the analytics team in Pittsburgh. And it’s that mix of new mechanics and new approach that has spurred his early success in San Diego (though in a very small sample size). Here’s a breakdown of some of those modifications:

Release Point

The mechanical adjustments in late 2019 allowed Musgrove to find a more consistent release point across his extensive 6-pitch repertoire. This can increase the “tunneling” effect that makes it more difficult for hitters to identify the pitch in a timely manner. Most notable is Musgrove’s more uniform extension point, which varied considerably early in his career, per this chart from Baseball Savant:

Spin Rate

Musgrove’s mechanical tweaks led to altered spin rates — especially on some key breaking pitches — and those changes have continued in 2021. (It’s worth noting that increased spin rate can be both good and bad, depending on the pitch. Fastballs, for example, typically benefit from more spin, while a handful of breaking pitches can benefit from less spin.) Here’s a look at the spin rate progression for Musgrove: 

Pitch 2019 Spin Rate 2020 Spin Rate 2021 Spin Rate
4-Seam Fastball 2419 2451 2587
Slider 2495 2677 2728
Curveball 2575 2712 2719
Sinker 2278 2294 2450
Changeup 2001 2078 2115
Cutter 2514 2512 2650

Horizontal Movement

As a result of the new spin rates and release points, several of Musgrove’s pitches are moving differently. That’s especially noticeable in his horizontal movement, which was already strong when the Pirates acquired him. Several of those pitches now boast top-level movement, per Statcast. Take particular note of the slider and curveball, which now have miniscule xwOBAs (expected weighted on-base average) of .141 and .159, respectively: 

Pitch 2019 Horizontal Movement 2020 Horizontal Movement 2021 Horizontal Movement
4-Seam Fastball -1.5 -0.8 1.7
Slider 6.4 7.6 9.3
Curveball 0.9 4.3 4.6
Sinker -3.6 -3.0 -3.9
Changeup -5.5 -0.1 -1.4
Cutter 1.0 -0.2 -0.9

(By the way, it’s fascinating to see that his fastball and cutter are now both moving the other direction, albeit in small amounts.) 

Pitch Mix

In 2020, the Pirates had Musgrove move away from his four-seam fastball — with -4.1 vertical movement — and more toward his curveball and slider. That change has been amplified in 2021, but the Padres also have Musgrove throwing more cutters than ever before. You can see the evolution of Musgrove’s pitch mix in this chart:

The last 35 pitches of his 112-pitch no-hitter on Friday consisted entirely of sliders, curveballs and cutters.

Barrels, Launch Angles and Whiffs

To some degree in 2020 and even more so in 2021, batters are having a harder time squaring up Musgrove’s pitches. In 2019, Musgrove saw a barrel rate of 6.4%. That dropped to 5.4% last year. With the Padres, that number has plummeted to 3.3% so far. 

At the same time, the launch angle on batted balls has dropped precipitously this year. After marks of 11.7 and 12.4 degrees in 2019 and 2020, respectively, Musgrove has induced a launch angle of just 1.6 degrees in 2021. That’s a lot of ground balls. 

Not only is Musgrove generating weaker contact, but he’s getting less contact. With the Pirates in 2019, his whiff rate was just 45%. Last year, that jumped considerably to 84%, and it sits at a strong 70% this year. That’s consistent in his put away rate, which was 19.7% in 2019 but went to 26.1% last year (8th among MLB starters) and 27.3% this season. 

Different Pitcher, Different Return

All of this has resulted in an xwOBA that has gone from .306 in 2019 to .273 in 2020 and just .241 this year in San Diego. Again, it’s still early, but it’s clear that Musgrove is a different pitcher than he was even two years ago. 

The Pirates’ staff deserves some credit for that. It would be nice to see Musgrove plying his newfound craft at PNC Park, but the reality is that the Pirates aren’t built to be contenders now. Cherington was justified in taking the gains of 2020 and flipping the 28-year-old Musgrove at his then-peak value for prospects Hudson Head, Omar Cruz, David Bednar, Drake Fellows and Endy Rodriguez. 

If it weren’t for the progress that Musgrove made in Pittsburgh, that kind of return might not have been possible. So while it’s tempting to lump Musgrove in with other ex-Pirate pitchers who have gone on to success, at least in this case, the Pirates benefited from his improvements.

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