Will The Red Sox Change Lucas Giolito's & Liam Hendriks' Pitch Mix in 2025?

In 2024, the league threw four-seam fastballs 32.3% of the time. Boston pitchers, on the other hand, threw them 18.7% of the time, down from 26.1% in 2023. Early in the season, when pitching coach Andrew Bailey was asked about this approach, the answer was simple: Four-seamers get hit harder, so the Red Sox want to throw fewer of them.

For pitchers like Isaiah Campbell, who was new to the team, this meant going from throwing fastballs 46.4% of the time in 2023 with Seattle to 19.3% with the Red Sox in 2024. He also increased his slider usage from 38.7% to 47.9%, which makes sense since 52% of his hits allowed came on fastballs compared to only 30.7% off his slider.

Those numbers show what the Red Sox saw in Campbell, making them want to acquire him and adjust his pitching mix. This made me wonder about Boston’s major free-agent signings from last season: Lucas Giolito and Liam Hendriks. While neither pitched last season, we can extrapolate what the Red Sox saw in them and what their pitching mix might look like once they hit the Fenway mound.

In 2023, Giolito threw his fastball 41.9% of the time while using his changeup 28.3% and his slider 28.5%. He gave up a league-high 41 home runs in 2023, but 18 came on fastballs while 12 came off his changeup, which means 11 came off his slider.

Brayan Bello is the 2023 Red Sox starting pitcher with the closest arsenal to Giolito. The biggest difference between their mix is that Bello has a two-seam fastball. In 2023, Bello threw his four-seamer 20.6% of the time and his two-seamer 36.3%. By 2024, his straight heater was used only 4.8% of the time, and his two-seamer was up to 40.3%. Still, that means that he went from throwing one of his two fastballs from 56.9% of the time down to 45.1%. If Giolito goes through roughly the same change in four-seam usage, he will throw his fastball at about 33.2%.

In 2023, Bello used his changeup 23.9% of the time and his slider 17.6%. Last season, those numbers increased to 26.9% for the change and 28% for the slider. If those ratios stay roughly the same for Giolito, we would see him throw his changeup 31.9% and his slider 45.3% of the time. I know those numbers add up to over 100%, but they are more to demonstrate the potential directional change and ballpark figure of the pitch mix. The fact that he could be throwing the pitch that got the best results for him in 2023, somewhere between 40-50%, could make a huge difference and should drastically decrease his home run totals.

In 2023, Liam Hendriks threw his fastball 58.6% of the time, his slider 39.1%, and his curveball just 2.3%. His best comp is Isaiah Campbell. So, if Hendriks undergoes a similar change, we’d see him throw his fastball to 24.4% and up his slider usage to 48.4%, with the remainder probably dedicated to his curveball.

Since 2020, Liam Hendriks has allowed 334 hits. 71% of those came off the four-seamer. Of his 68 home runs allowed, 79.4% came on heaters. So, under Andrew Bailey and the Red Sox's new pitching regiment, they hope that limiting Hendriks and Giolito’s most-hit pitch can turn them into a similar success story as what we saw with Tanner Houck and Kutter Crawford. Hendriks was an elite closer not long ago, and although Giolito has a little more separation from his glory days, there is reason to believe that as long as both are healthy, they can get back at least close to those numbers.