September 9, 2025

Game Preview

Written by: Jake Turner

Jake is a veteran sports analyst with over 10 years of MLB prop betting experience.

Cardinals vs Mariners: Betting Preview & Props (Sep 09)

Last updated: September 09, 2025

Game Time: 9/9, 09:40PM

Game Overview

The St. Louis Cardinals face off against the Seattle Mariners in a late-night matchup. The Mariners are strong favorites, with DraftKings listing them at −220, while the Cardinals are +178 underdogs. A significant 70% of the betting public is backing the Mariners, highlighting the perceived advantage for the home team.

Pitching Preview

Pitching Matchup: Matthew Liberatore vs George Kirby

Matthew Liberatore (STL):

Arsenal: Four-Seam Fastball (29% usage, 93.9 mph), Slider (22% usage, 86.4 mph), Curveball (15% usage, 77.4 mph), Changeup (12% usage, 88.5 mph), Cutter (11% usage, 90.1 mph), Sinker (11% usage, 94.0 mph)
Interpretation: Liberatore is a mix artist with a balanced pitch distribution, leaning on a diverse range of speeds and movements.
Matchup Insight: The Mariners lineup averages .252 this season with a projected xBA of .241 against Liberatore's offerings, indicating potential struggles.

George Kirby (SEA):

Arsenal: Four-Seam Fastball (29% usage, 96.1 mph), Slider (28% usage, 87.1 mph), Sinker (24% usage, 96.1 mph), Curveball (13% usage, 84.3 mph), Splitter (3% usage, 86.0 mph), Changeup (2% usage, 87.5 mph)
Interpretation: Kirby relies heavily on power pitches with high velocity, aiming to overpower hitters with his fastball and sinker.
Matchup Insight: The Cardinals lineup averages .251 this season but projects to hit .250 against Kirby, showing a slight neutral effect from his pitch arsenal.

Lineup Advantage vs Arsenal

Lineup Matchups & Batting Edges

For the Cardinals vs George Kirby:

The Cardinals lineup averages .251 this season but projects to a .250 average against Kirby's arsenal.
Biggest Increase: Thomas Saggese shows a slight improvement, with a season BA of .242 → xBA vs arsenal .260 (+18 points), and a decrease in K% from 28.7% → 23.7% (-5.0%).
Biggest Decrease: Iván Herrera faces a significant drop, with a season BA of .283 → xBA vs arsenal .223 (-60 points), and an increase in K% from 19.3% → 23.6% (+4.3%).

For the Mariners vs Matthew Liberatore:

The Mariners lineup averages .252 this season but projects to a .241 average against Liberatore's arsenal.
Biggest Increase: Data not available for positive changes.
Biggest Decrease: Julio Rodríguez's performance could dip, with a season BA of .250 → xBA vs arsenal .237 (-13 points), and an increase in K% from 22.5% → 26.9% (+4.4%).

Lineup Strikeout Trends vs Arsenal

Strikeout Risks & Rewards

The Cardinals' projected K-rate is 22.4% vs George Kirby, up 0.5% from their 21.9% season average.
The Mariners' projected K-rate is 24.8% vs Matthew Liberatore, up 3.3% from their 21.5% season average.

Behind the Plate

Behind the Plate: Umpire assignment has not been announced, which makes prop volatility a concern.

What to Bet On

📢 Prop Alert: Thomas Saggese (.242 → .260, +18 points) shows a notable batting improvement against Kirby, but lacks the criteria for a strong betting lean.
⚡ No K Prop Alerts: No significant strikeout prop opportunities meet our criteria.

🔑 Key Takeaways

Matthew Liberatore's diverse pitch mix may challenge the Mariners' lineup, which is projected to underperform slightly against his arsenal.
George Kirby's velocity-heavy arsenal poses a potential challenge for the Cardinals, though their lineup shows minor adaptation.
No significant umpire impact due to the lack of assignment details, contributing to prop volatility.
With no standout prop alerts, bettors may find limited value in this matchup's offerings.

🧠 FAQs

Q: Who is the best betting prop for the STL vs SEA game? A: No players meet our strict betting criteria for this game.

Q: Is the umpire a pitcher-friendly umpire? A: Umpire assignment is TBA, making the tendencies unknown.

Q: What time is the STL vs SEA game? A: The game starts at 9/9, 09:40PM.

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