After returning from a right tricep injury that sidelined him for nearly all of August, Joe Musgrove was elite in September.
Over 25 innings pitched, the right-handed 27-year-old allowed just six earned runs (2.16 ERA). He struck out 38 batters while walking five. Of the 98 batters he faced, only 18 registered a hit. The sample size is small. That said, Musgrove wasn’t lucky this past September. He was dominant.
In his five September starts, Musgrove’s average exit velocity allowed was a measly 84.1 mph. For reference, Kenta Maeda allowed the lowest qualified average exit velocity in 2020 at 85.3 mph. When he wasn’t striking out batters at a 38.8 percent clip, Musgrove was forcing ground balls 55.6 percent of the time when he allowed contact.
So what happened? What made Musgrove an elite starting pitcher during this small timeframe? Is his success sustainable moving forward?
In past seasons, Musgrove threw his fastball about 50 percent of the time. In 2020 though, that rate dropped to 39.1 percent. Before this season, Musgrove never threw his curveball more than ten percent. This season, his curveball rate doubled to nearly 20 percent.
In 2020, opponents hit .314/.395/.676 against Musgrove’s four-seamer. In other words, his fastball got crushed. Over his career as a whole, opponents have slashed a juicy .284/.351/.515 line against his cheese. It’s not an effective pitch for him. Not only can he afford to throw it less. He needs to be throwing it less.
On the other hand, opponents hit .050/.136/.050 against Musgrove’s curveball in 2020. Over his career, they have slashed .195/.241/.383 against the pitch. It was far and away his best pitch in 2020.
The formula is simple moving forward. Keep throwing less fastballs. Continue to throw more curveballs and sliders (his other best pitch).
Moving forward, if Musgrove uses the same pitch mix as he did in September, I believe he can become the four to five win pitcher that the Pirates desperately need him to be.