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St. Louis Cardinals at Seattle Mariners prediction, pick for Tuesday 9/9/25

St. Louis Cardinals at Seattle Mariners prediction, pick for Tuesday 9/9/25

Published:

By: Charlie Cummings

There have certainly been better times to be a Cardinals or Mariners fan. A brutal season in St. Louis has seen attendance plummet while the team fights to stay in the National League Wild Card picture. Meanwhile, after going all-in at the trade deadline, Seattle is flailing and fighting to stay above the teams nipping at its heels. Tonight’s winner only feels a tad safer, while the loser continues to spiral. Talk about some stakes.

The Mariners enter as -217 moneyline favorites on DraftKings Sportsbook. The total is set at 7.5 runs. Let’s dig into a preview, prediction and best bet for this Cardinals vs. Mariners matchup.


Cardinals at Mariners prediction, preview

If you felt like your season was on the line, turning to George Kirby doesn’t sound like a bad idea. But in this season, that has not been the case. His hard-hit rate and expected ERA are the worst of his four-year career, and he’s not generating consistent outs with his fastball, exposing his lack of great secondary pitches. His two worst starts by total earned runs and hits allowed have occurred in his last four outings. Even against a struggling St. Louis offense, his presence could be a problem.

His opposite number, Matthew Liberatore, has not fared much better. The former top prospect has yet to put it together in St. Louis and has a 4.60 expected ERA this year, according to Baseball Savant. His fastball is getting teed up, and he can’t keep the ball on the ground consistently — a bad equation when you can’t rack up the strikeouts. For a Mariners offense that just put up 29 runs across three games against the Braves, this is a feast spot.

I have a hard time trusting these pitchers, even in the humidity and cool Seattle weather. Count on the over in this one.

Best Bet: Over 7.5 Total Runs

I am a promoter at DraftKings and am also an avid fan and user and may sometimes play on my personal account in the games that I offer advice on. Although I have expressed my personal view on the games and strategies above, they do not necessarily reflect the view(s) of DraftKings and do not constitute a representation that any particular strategy will guarantee success. All customers should use their own skills and judgment in building lineups. I may also deploy different players and strategies than what I recommend above. I am not an employee of DraftKings and do not have access to any non-public information.