To say this is the biggest start of Keider Montero's career seems too cliché, but how things have gone with the Detroit Tigers in the month of September, perhaps it's not too far-fetched. With Charlie Morton getting shelled in Friday's loss to Atlanta, the Tigers will need a strong start from Montero on Saturday.
The offense has been the primary issue for the Tigers during the last week however, if Montero can go and keep Atlanta, who has won six in a row, to limited damage, the Tigers can hopefully get to former Detroit lefty Joey Wentz, who will be looking for some revenge. This tweet got me thinking about Montero and how he can neutralize Atlanta.
Key Factor: 2025 to 2024: Changeup Growth
The most important development for Montero this season has been the rise of his changeup. In 2024, it was a background pitch—thrown just 10.7% of the time, with mixed results. In 2025, it has become his best weapon by wOBA allowed, even as usage has only nudged up to 12.2% (Baseball Savant). With nearly 15 inches of horizontal fade and more than 30 inches of drop, the pitch now consistently generates weak contact and chases, making it the clear separator in his arsenal.
Against a Braves' lineup that punishes mistakes, the question is whether Montero will push that usage higher, closer to 18–20% to neutralize their most dangerous bats.
Slider: A Swing-and-Miss Weapon
While the changeup is his most effective pitch by results, Montero’s slider is his highest whiff pitch in 2025, generating a 35.6% whiff rate, up significantly from 25.7% in 2024. That jump shows the slider has become his go-to swing-and-miss option, even if its run value doesn’t look elite on paper.
Thrown 22% of the time this season, the slider gives Montero a legitimate finishing pitch. It pairs especially well with the changeup: one fades arm-side and down, the other breaks glove-side. When tunneled from the same release point, the two pitches pull hitters in opposite directions, forcing uncomfortable swings. So how could this work against lefties and righties?
- RHB Sequencing: Fastball up - changeup fading arm-side below the zone -slider breaking glove-side. This three-pitch tunnel forces hitters to guard both sides of the plate and speeds.
- LHB Sequencing: Start with slider back-foot or sweeping across the zone -follow with changeup fading away. The slider sets up the chase, the changeup closes the at-bat.
According to Savant, Montero’s slider hasn’t carried great results in isolation (negative run value), but when it plays off the changeup, the sequencing effect is real. The slider makes hitters commit early, while the changeup punishes over-aggressiveness.
Braves Lineup: Changeup Matchups
- Jurickson Profar (LF): Contact-oriented bat with more success against heaters. A well-located changeup below the knees can get him to roll over.
- Matt Olson (1B): A dangerous lefty who has produced a positive run value vs. changeups this year. The game plan should be fastballs up and breaking balls away—using the changeup only as a chase pitch off the plate.
- Ronald Acuña Jr. (RF): Elite bat speed. Best chance to disrupt him is sequencing—establish the fastball and sneak a low changeup early in the count.
- Drake Baldwin (DH): Still adjusting to MLB-level off-speed. Changeups fading away can induce ground balls or whiffs.
- Ozzie Albies (2B): Carries a negative run value vs. changeups in 2025. This is a prime target for Montero’s best pitch, especially late in counts.
- Ha-Seong Kim (SS): Patient and disciplined, but his profile suggests he can be beaten with well-placed changeups away.
- Michael Harris II (CF): Another hitter with a negative run value vs. changeups this season. Montero can expand the zone down and away to take advantage.
- Sandy León (C): Veteran catcher with diminished bat speed. A steady diet of fastball-changeup tunnels should keep him quiet.
- Nacho Alvarez Jr. (3B): Young, inexperienced bat. Montero can expand with the changeup off the plate and look for swing-and-miss.
Strategic Path
The lineup card favors a heavier dose of change ups. Four Braves starters today (Albies, Harris II, Ozuna if available, and Profar) all carry negative run values vs. the pitch, while only Olson has shown consistent success against it. That balance tilts the plan toward Montero’s most improved offering.
The execution piece is simple but critical: keep the changeup down or fading off the plate. The Braves’ hitters who do damage against it thrive when it’s left in the strike zone. Montero doesn’t need to completely abandon his four-seamer or slider, but he has to trust the changeup more often, especially as a finishing pitch.
Get It Done
This start may indeed be the biggest of Montero’s career, and the numbers point to a clear path. The 2024 to 2025 growth of his changeup gives him a legitimate weapon against a red-hot Atlanta team. If he leans on it more heavily, while staying disciplined with location, Montero has the chance to turn a daunting matchup into the outing the Tigers desperately need.