Starting Pitcher Pitch Mix Change in June and July: Fewer Fastballs

One way to find starting pitchers who have been making pitch mix changes is to see who is throwing fewer or more fastballs (four-seamers and sinkers). The table below shows the starting pitchers who have thrown fewer four-seamers and sinkers in June and July. I used a 3-percentage point dip as a cutoff.

I included the average wOBA for their four-seamers and sinkers to show whether it’s a pitch that has been hit hard or not. When a pitcher throws fewer fastballs, there’s probably a reason why. While we would love to examine all these starting pitchers on the list, it provides a starting point.

Let’s examine four starting pitchers who have been throwing fewer fastballs and whether that’s helpful in their arsenal. We covered a fifth name on this list, Joey Cantillo, in a recent swing timing and miss distance article. 

Bubba Chandler, SP, Pirates

Chandler has been gradually lowering his four-seam usage throughout the season. He was throwing four-seamers 44-46% of the time in May and June. That dropped to 38.3% in two July starts. That coincided with Chandler throwing more sliders in May (15.5%), June (24.8%), and July (23.5%). Meanwhile, Chandler’s changeup and sinker usage have been fluctuating throughout the season.

Some of Chandler’s four-seam metrics look intriguing, with 17.9 inches of induced vertical break, a 105 Stuff+, and 6.6 feet of extension (65th percentile). The four-seam results have been better against right-handed hitters (.323 wOBA, .309 xwOBA) compared to lefties (.352 wOBA, .373 xwOBA). Theoretically, Chandler’s four-seam outcomes could be better with better command, however, it makes sense to back off the fastball in the short term.

As noted, Chandler appears to have reduced his fastball usage in exchange for more of his gyro-like slider. That pitch has an additional two inches of vertical rise this season vs. last, but the Stuff+ rating on the pitch has actually decreased a bit, from 115 last year to 112 this. While that is a pretty small change, Chandler’s command of his slider has taken a bigger hit, with his location+ dropping by 13 points to a 102 this year. 

That’s interesting because Chandler’s slider gained whiffs (14.5% swinging-strike rate) and the heatmaps have been more concentrated this season. For context, Chandler’s slider generated a 9.9% swinging-strike rate while throwing it less often in the zone (42.1%) by over seven points this season. There’s a chance that opposing hitters could be sitting on his pitches like the slider, leading to mixed results. 

In most formats, it’s hard to latch onto more than blind faith for Chandler to perform better this season.

Shota Imanaga, SP, Cubs

Imanaga dropped his four-seam usage to 27.7% in two July starts, the lowest in any month during his career. That coincided with more splitters (35.6%) and sweepers (20.7%), though the splitter usage has been fluctuating throughout the season. 

Though Imanaga has only thrown his sinker 6.5% of the time, he has been using it steadily only dipping below 5% in one month so far this year. That’s notable because, prior to this season, he had only used the sinker more than 5% of the time in a month once, back in September of 2024. Against right-handed hitters, Imanaga cut his sweeper usage by five points (5.9%) and mixed in more sinkers (6.2%) as his third and fourth option behind the four-seam (42.6%) and splitter (40.3%). 

The sinker is a pitch-to-contact offering, allowing an 86% contact rate this season. That makes sense since Imanaga’s sinker allows a .286 batting average and .344 wOBA (.325 xwOBA) against righties. He attempts to throw the sinkers lower in the zone against right-handed hitters, though they often hit it hard when they’re thrown toward the inside corner. 

Since Imanaga often faces right-handed hitters, there might be some noise in the lefty splits. Unfortunately, Imanaga throws his sinker in the heart of the zone to lefties, leading to opposing hitters doing damage. That’s evident in left-handed hitters rocking a .492 wOBA (.373 xwOBA) while he throws them 7.4% of the time, up over two percentage points from 2025. 

With Imanaga throwing slightly more sinkers, he is throwing his four-seamer 37.7% of the time against lefties, the lowest of his career (typically at 49% or higher). The more notable pitch mix changes against left-handed hitters are fewer four-seamers, plus more sweepers and splitters, both of which have been thrown five points more this season. 

Finally, let’s highlight Imanaga’s splitter. His splitter has been eliciting a 24% swinging-strike rate with similar stuff grades (90 Stuff+) and slightly better command (112 Location+). He was throwing his splitter in the zone more often last season (49.9% zone rate), but it’s back down to 40.5%, similar to 2024. It’s a small sample, but Imanaga’s splitter has specifically been inducing more whiffs (30% swinging-strike rate) against lefties this season, compared to 20% last year. 

Though splitters can be volatile, it’s positive to see Imanaga generate whiffs via his best pitch. Most of Imanaga’s underlying metrics suggest he is back to his rookie season form. The only small difference is Imanaga’s 34.1% ball rate this season, up from 32.4% (2025) and 31.5% (2024). That coincides with Imanaga throwing fewer pitches in the zone (46.3%), which might help him elicit whiffs while maintaining a slightly higher ball rate. 

There might be a buying opportunity in trading leagues, with the slightly better expected ERA metrics in xERA and SIERA. 

Kyle Leahy, SP, Cardinals

After only making one start across 98 games in his first three seasons, Leahy made 19 starts and passed his career high in innings this year (95.1 innings). I might have a bias against the Cardinals’ starting pitchers — they’ve been in the bottom 10 in K-BB% and SIERA as a team — so I have overlooked Leahy. However, these types of exercises where we find pitchers looking for something like a change in pitch mix are ideal for highlighting names you might not otherwise notice.

Throughout Leahy’s career, he is lowering his four-seam usage, which is down to 28.2% this season. That made sense because Leahy’s four-seam had been crushed in 2024 (.372 wOBA, .433 xwOBA). It improved in 2025 (.318 wOBA, .343 xwOBA), but is again performing worse this season (.414 wOBA, .427 xwOBA). Specifically, left-handed hitters have been performing well against the four-seamer, with a .425 wOBA (.443 xwOBA) this season. 

He was throwing his four-seamer around 30% in April and May, dipping to 25.7% in June and 23.6% in July. That coincides with more sliders and changeups in June and July. He is throwing his changeup over two points more to lefties this season (21.9%), but the results have been mixed, as the pitch leads his arsenal in whiffs (16.9% swinging-strike rate), but is allowing a .314 wOBA (.360 xwOBA) to lefties.

Throughout the season, Leahy’s slider and sweeper usage have fluctuated. Both his slider (.209 wOBA, .290 xwOBA) and sweeper (.360 wOBA, .315 xwOBA) have been relatively effective against right-handed hitters, so it makes sense to lean on them often, like he does, to account for over 40% of his arsenal.  

Against right-handed hitters, Leahy has been throwing nearly twice as many sinkers (24.4%) in 2026 vs. 2025. The sinker has been performing decently to limit hard contact against righties, including a .243 wOBA (.329 xwOBA). He uses it to generate contact, with a 95.7% contact rate while pounding the zone 60.6% of the time. 

Leahy uses his elite extension (7.3 feet, 96th percentile), which likely helps his below-average stuff (90 Stuff+) perform better than expected. He has shown above-average command (105 Location+), with all five of his primary pitches having a Location+ at 101 or higher this season. At best, Leahy profiles as a deep-league streamer, though he can hurt your WHIP since he allows tons of balls in play. 

Ryan Weathers, SP, Yankees

Weathers lowered his four-seam usage (27.9%) to right-handed hitters this season. That’s a pretty sizable decrease from 45.3% (2025) and 41% (2024). He hasn’t replaced those four-seamers with just one pitch, and has instead made smaller increases in usage of his sweeper (18.3%, nearly a two-point increase), slider (9.4%, a five-point increase), and sinker (15.5%, a 13-point increase). Wildly enough, Weathers’s four-seam has been struggling against righties (.427 wOBA, .436 xwOBA) with the lowered usage. 

The four-seam command grade has been better (110 Location+) this season, up from 105 last year. However, the four-seam heatmaps tend to look similar against right-handed hitters. When he leaves the four-seamer in the heart of the zone, opposing hitters have been making contact 90.4% of the time and doing damage.

There’s a chance that Weathers’ new lower arm angle (33 degrees), down eight degrees from 2025 (41 degrees), makes the four-seamer more hittable. That’s notable because he is locating his four-seamer two inches more toward the heart of the plate to righties.  However, it looks like the four-seam results against righties last season might be the outlier, meaning right-handed hitters may continue to hit them hard.

There’s value in Weathers throwing more sinkers to right-handed hitters. The sinker drops over 7 inches more with over 8 inches of arm-side fade compared to the four-seamer. Weathers’s sinker locations have varied this season, as he has been throwing more toward the low and inside corner to right-handed hitters. When Weathers was throwing more sinkers to righties in 2024, he was peppering them low and away from right-handed hitters. 

We’re probably digging into the weeds because Weathers has a career-best in K-BB% (19.9%), decent swinging-strike rate (11.8%), above-average command (109 Location+), and a 3.46 SIERA that points toward better results moving forward. It makes sense for Weathers to lean more on the non-fastballs, as a pitcher that’s continuing to evolve.

There’s a chance to buy low on Weathers based on the skills and command, though he has already set a career high in innings (102.1) this season, and fantasy managers need to be aware of workload expectations for the rest of the season.