Is Padres' trade pickup on verge of breakout?

January 19th, 2021

In recent years, we've seen and reach ace status after being traded away from Pittsburgh. Is next?

With Tuesday's three-team trade official, the right-hander is the newest member of the Padres, three years after he joined the Pirates in the deal that sent Cole to the Astros. That wasn't Musgrove's first time being traded, as he previously was dealt from the Blue Jays to Houston in a package for in 2012.

Musgrove's ceiling is still not entirely clear, but he appears to be trending in a promising direction, with two years of team control remaining. His career 96 ERA+ suggests he’s a slightly below-average arm. However, he has recorded a 3.69 FIP over the past three seasons, tied with Cardinals’ ace for 27th among the 75 big league qualifiers in that span.

Musgrove, 28, also had his best season in 2020, posting a 3.86 ERA (116 ERA+) with the 10th-highest strikeout rate (33.1%) in MLB (min. 30 innings). His xERA was 3.23, a bit better than the 3.26 xERA posted by 33-year-old righty , who was traded to the White Sox in December.

While it was a small sample size of only eight starts, Musgrove is an intriguing addition for San Diego. Here are some of the factors to consider when evaluating Musgrove's future value.

His curveball could be an elite weapon

Over his first four seasons, Musgrove used his curveball only 7.5% of the time and recorded an average spin rate of 2,547 rpm with the pitch. The league average spin rate on curveballs in that span was 2,493 rpm.

Last season, though, he leaned on his curveball more often, throwing it nearly 20% of the time. He also bumped his spin rate to 2,712 rpm and generated above-average vertical and horizontal movement, getting 2.9 more inches of drop and 4.4 more inches of break than the average curveball.

As a result, the pitch morphed into one of the most devastating offerings in the game.

Highest whiff rate on any single pitch type, SP, 2020
Min. 25 swings vs. that pitch
1. Blake Snell’s curveball: 61.8%
2. Shane Bieber’s slider: 61.2%
3. Corbin Burnes’ slider: 55.2%
4. Shane Bieber’s changeup: 53.7%
5. Joe Musgrove’s curveball: 53.2%

Among the 128 hurlers who ended at least 20 plate appearances with a curveball in 2020, only six allowed a lower xwOBA and just two had a better xBA on curves than Musgrove (.148 xwOBA, .080 xBA), who held batters to one hit in 20 at-bats with 13 strikeouts on curveballs.

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His slider, too

Musgrove’s curveball wasn’t the only one of his breaking pitches that baffled hitters in 2020. The righty also dominated with his slider, which has long been his most effective offering.

Remember when Musgrove struck out swinging on a pitch that hit the superstar shortstop in the back leg in September? It was a wicked slider that did the trick, netting Musgrove one of 10 K's over seven shutout innings in his final start of the season.

As he did with his curveball, Musgrove got above-average vertical and horizontal movement with his slider. In fact, he ranked 10th among qualifiers in horizontal slider movement, generating 7.5 more inches of break than the average slider.

The righty limited batters to a .187 xwOBA on sliders last season, tied for 30th best among the 225 pitchers who ended at least 20 plate appearances with the pitch. And of the 77 swings he got on sliders in 2020, more than half (50.6%) were whiffs.

That made Musgrove one of two starters to register a whiff rate of 50% or better on multiple pitch types (min. 25 swings per pitch). The other? Indians right-hander , the reigning American League Cy Young Award winner.

Using the same criteria, only 10 starters even reached the 40% threshold on multiple pitch types in 2020. In addition to Musgrove and Bieber, the list includes Cole, Snell, , , , , and .

Combined, Musgrove used a breaking ball 44.1% of the time in 2020, giving him the 15th-highest rate in MLB (min. 500 total pitches). Only seven pitchers allowed a lower xwOBA on breaking pitches.

Lowest xwOBA on breaking balls, 2020
Min. 50 plate appearances ending on breaking balls
1. Corbin Burnes: .118
2. Blake Snell: .128
3. Christian Javier: .134
4. Tyler Glasnow: .141
5. Zach Plesac: .155
6. Dylan Bundy: .157
7. Dinelson Lamet: .162
8. Joe Musgrove: .175
9. Tejay Antone: .183
10-T. Trevor Bauer: .188
10-T. Shane Bieber: .188

What’s holding him back?

Musgrove's four-seam fastball, which sits between 92-93 mph, has been at the root of his inconsistency during his five-year career. This runs in contrast to Cole and Glasnow, who both have elite four-seamers.

Musgrove gets above-average spin on his four-seamers, but his active spin -- the spin that contributes to movement -- has been among the worst in the game in each of the past two years, which explains why his four-seamer has ranked poorly on the vertical movement leaderboard year after year.

Fastballs with less rising action generally miss fewer bats, and Musgrove’s fastball generated 4.1 inches less rise than the average four-seamer in 2020, leading to a whiff rate on four-seamers (17%) that was well below the MLB average (22.6%).

Musgrove did decrease his four-seamer usage in 2020, throwing it 27% of the time (37.6% in ’19), but it was still the most used pitch in his arsenal and yielded a .369 xwOBA.

Musgrove also throws a sinker and a cutter in addition to his four-seamer, but he hasn't been able to establish any of his fastballs as a consistently reliable setup pitch for his slider, curve and changeup. Perhaps he never will. But considering how good his breaking stuff was in 2020, it will be interesting to see if he can unlock his full potential.