5 Starting Pitchers on New Teams Making Pitch Mix Changes

It’s been around two weeks since the MLB Trade Deadline. That’s a sample of 2-3 starts for these starting pitchers with their new teams. Though we’re dealing with a small sample, it’s enough to look and see if these players could be making pitch mix adjustments with their new teams.

We’ll examine pitch mix changes and whether it’s helpful to their arsenal moving forward. As with anything fantasy baseball-related, we want to rely more heavily on the larger sample than recent changes. However, the pitch mix adjustments with their new teams could be a signal of future changes in their arsenal. Let’s cover five starting pitchers who have been changing their pitch mix with their new teams.

Luis Castillo, SP, White Sox

Castillo threw seven scoreless innings with 10 strikeouts against the Reds last week. The last time Castillo struck out 10 batters was in September 2025. It was the first time Castillo generated 20 or more whiffs in a game since June 2024. Specifically, against the Reds, Castillo dropped his slider usage to 5.4% against left-handed hitters.

Castillo has been throwing his changeup more often (32.6%) to left-handed hitters with the White Sox. For context, Castillo’s changeup usage against lefties is up from 18.4% (July) and 21.1% (June). That’s a notable change because Castillo’s changeup has been allowing a .205 wOBA (.222 xwOBA) against lefties in August. 

Furthermore, Castillo is throwing his sinker (19.9%) slightly more, 6 percentage points higher than in July. It’s a small three-game sample, but Castillo’s sinker has been inducing ground balls with a -2 launch angle in August, significantly lower than his season-long 13-degree launch angle against left-handed hitters. 

With the Mariners, Castillo’s groundball rate was around 38-41% before 2026 (37.7%), significantly different from those previous seasons in Cincinnati. If Castillo can generate more whiffs via the changeup and ground balls from the sinker, it could be a notable change for him moving forward. 

Castillo’s upcoming schedule is a mixed bag, with the Mets, Twins, and Astros over the next few weeks. His outing with 20+ whiffs and 10 strikeouts is probably an outlier, but monitor the pitch adjustment against lefties.

Tyler Mahle, SP, Braves

Mahle threw back-to-back quality starts with the Braves against the Yankees and Mets in his first two games with the new team. He increased his splitter usage in August, throwing them 33.5% of the time while lowering the cutter (17.6%) and slider (0.7%) usage. For context, Mahle was throwing his splitter 23.5% of the time in July and 30.3% in June.

Mahle consistently threw his splitter to left-handed hitters in August (35.7%), close to his season-long average (33.1%). However, Mahle began throwing his splitter significantly more against right-handed hitters (30.7%) in August, up from 11.2% (July) and 17.1% (June). Mahle’s splitter allows an .089 wOBA (.268 xwOBA) against right-handed hitters in August, better than the season-long numbers (.301 wOBA, .373 xwOBA). 

The stuff models don’t like Mahle’s splitter (82 Stuff+), likely because it has below-average downward movement, yet plenty of arm-side fade. When Mahle’s splitter is cooking, it fades toward his arm-side by 13-14 inches. Mahle commands his splitter well with a 113 Location+. 

He locates the splitter low and away from left-handed hitters. Meanwhile, Mahle has been lowering the zone rate (48.6%) on his splitter against right-handed hitters, down over 10 percentage points from 2025. That’s still a relatively high zone rate for splitters, especially when comparing it to lefties (37.2%). For context, the league-average zone rate for splitters is 38.8%. 

Besides throwing more splitters, Mahle’s ERA estimators have been optimistic, given his 3.93 xERA and 4.03 SIERA with a 14.7% K-BB%. Maybe I shouldn’t have questioned the Braves for not making a bigger starting pitcher move at the deadline. This should make us more intrigued with Mahle since the ERA estimators expected regression while throwing one of his better pitches more often.

Dustin May, SP, Brewers

May’s cutter usage exploded to 35.6% in August, up from 22.6% in July and 16.4% in June. He is throwing his cutter more to left-handed hitters (38.5%) and righties (29.3%) in August. For context, May threw his cutter 28.7% of the time against lefties and 14.3% against right-handed hitters this season. The cutter has been decent against left-handed hitters, allowing better results (.321 wOBA, .306 xwOBA) than in previous seasons.

Right-handed hitters have been performing well against the cutter (.353 wOBA, .294 xwOBA) this season. Though May’s cutter surface results were better in the past against right-handed hitters, he was only throwing them 6-7% of the time before 2026. He commands the cutter well with a 111 Location+, leading his arsenal, so it makes sense for the Brewers to help him evolve and throw it more often. 

I wrote about May’s arm angle before the trade to Milwaukee, and Jack Martin discussed May in his article on the power sweeper. So far, it seems that the Brewers worked with May to throw more of the pitch he commands better, as one of three pitches with a Location+ at 102 or higher, including the sinker (102) and changeup (104). 

May threw two quality starts in a row with the Brewers and joined the top pitching organizations in the majors. Don’t be surprised if May finishes the season strong, making him a popular draft target next season.

Robbie Ray, SP, Padres

Ray has been leaning on his changeup 31.8% of the time while lowering his four-seamer (20.5%) and sinker (18.2%) usage in August with the Padres. He mainly throws his changeup against right-handed hitters, increasing by 7+ percentage points from last season (16.7%). That’s notable because Ray’s changeup has been performing well, with a .206 wOBA (.246 xwOBA) this season. 

Before 2025, Ray last threw his changeup 4.3% of the time in 2021. Ray is throwing his changeup over 1 mph harder this season. The changeup has a movement profile similar to the 2025 version. The Stuff+ models don’t like the changeup (82 Stuff+), but his command has been better (97 Location+) than his career average (92). He locates the changeup low and below the zone, though he might benefit from throwing it more outside the zone. 

Ray throws his changeup in the zone 48% of the time, with opposing hitters chasing outside the zone 30.5% of the time. For context, the league-average changeup zone rate (36.8%) is over 10 points lower, with a similar league norm for chase rate (28.9%). 

After primarily throwing four-seamers and sliders while sprinkling a knuckle curve and sinker, Ray throws five pitches at 10% or more. That includes a consistent drop in Ray’s four-seamer usage in August compared to his season-long average (33.3%). The Stuff+ models still think Ray’s four-seamer is above-average, with a 105 Stuff+, but the command has dipped (93 Location+) this season, compared to his career average (100).

Ray’s four-seamer has been hit harder by right-handed hitters (.376 wOBA, .379 xwOBA) and lefties (.356 wOBA, .358 xwOBA) compared to last season. It’s slightly worrisome that Ray’s four-seam results are worse against righties while he is throwing fewer of them (35%), a 14-point decline in usage. Similarly, Ray cut his four-seam usage in half to 28.2% to left-handed hitters with worse outcomes. 

The pitch mix change is interesting for Ray. However, regression could hit hard with a 4.57 xERA and 4.87 SIERA being over 1 run higher than his actual ERA. He isn’t generating weak contact with the lowest K-BB% (8.7%) since 2020 (9.2%) when we toss out 2023 (-10.5%) and Ray’s 3.1 innings. Be cautious with Ray sustaining his success.

José Soriano, SP, Blue Jays

Soriano has been leaning more on his sinker (38%) in August, up from 28.6% (July) and 22.9% (June). That coincided with Soriano throwing fewer four-seamers (17.4%), 5-7 percentage points lower than the previous two months. His sinker usage is down to 30.6% against right-handed hitters, as he mixed in more four-seamers this season. 

That said, Soriano’s sinker has been one of his best pitches against right-handed hitters, allowing a .224 wOBA (.315 xwOBA) this season. However, Soriano’s sinker has been hit hard in August against right-handed hitters (.381 wOBA, .401 xwOBA). Given a larger season-long sample of success via the sinker, it makes sense for Soriano to throw it more often against righties. 

Meanwhile, Soriano’s sinker usage dropped by over 12 percentage points against left-handed hitters this season, compared to 2025. However, we’ve seen Soriano throw more sinkers against lefties in August (35.8%) than in July (28.2%) and June (17.7%). 

The Blue Jays may be working with Soriano on throwing more sinkers, especially since he commands them well, with a 108 Location+ while it’s his best pitch in Stuff+ (104).  However, Soriano’s sinker hasn’t been performing well in August (.356 wOBA, .447 xwOBA), similar to the season-long outcomes (.391 wOBA, .438 xwOBA) against left-handed hitters. 

Maybe the higher sinker usage will help generate more ground balls, which have fallen off from his career average (58.8%). Theoretically, it will help induce weak contact and support a better xERA (4.52). Soriano has been fortunate, with a 3.82 FIP and 3.72 xFIP being the only ERA estimators under 4.00. Though we’ve seen Soriano maintain a 13.2% swinging-strike rate, his control remains problematic with a 37.5% ball rate this season, which aligns with his career norm (38%). 

The increased sinker usage is notable, though we hope it doesn’t lead to a consolidated arsenal, because his diverse mix of pitches has been fruitful this season with the sinker, knuckle curve, four-seam, and splitter thrown relatively evenly, accounting for 95% of his arsenal.