Kansas City Royals vs Seattle Mariners Picks and Predictions September 18th 2025

Mariners vs Royals Picks and Predictions — September 18, 2025

The Seattle Mariners travel to Kauffman Stadium to face the Kansas City Royals on Thursday night. Seattle (83-69) is fighting for playoff positioning in the AL West, having won nine of its last ten before dropping Wednesday’s contest. Kansas City (76-76) remains at .500 and looks to build off a 7-5 win in the series opener, as shown in the recent MLB scoreboards.

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Opening odds:

• Moneyline: Mariners −123, Royals +105
• Runline: Mariners −1.5 (+129), Royals +1.5 (−154)
• Total (Over/Under): 9.0 runs

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Mariners Can Win If…

• Luis Castillo pitches to his form. With a 3.76 ERA, Castillo gives Seattle a veteran edge on the mound and can stabilize the game after Wednesday’s defeat.
• The lineup leans on power. Seattle ranks 2nd in MLB with 223 home runs, led by Cal Raleigh’s league-best 56 bombs.
• Supporting bats keep contributing. Eugenio Suárez went 4-for-4 with a homer in the last meeting, and J.P. Crawford also went deep — that balance matters against Kansas City’s staff.

“We know our offense can break games open with one swing,” Mariners coaches said earlier this season.

Royals Can Win If…

• Stephen Kolek delivers another steady outing. He enters with a 3.71 ERA and a 1.20 WHIP, capable of matching Castillo pitch-for-pitch.
• Their lineup stays aggressive. KC ranks 4th in doubles (267) and got key blasts from Salvador Perez and Adam Frazier in their 7-5 win Wednesday.
• Vinnie Pasquantino continues producing. With 30 HR and 104 RBIs, he anchors an offense that thrives on extra-base hits.

“We have guys who can drive the ball and change the game quickly,” Royals staff noted after their series-opening victory.

Key MLB Betting Trends

The Lean

Pick: Mariners Moneyline (−123)
Projected Final Score: Mariners 5, Royals 4
Total Lean: Under 9.0

Reasoning: Seattle’s form and lineup power give them the advantage, especially with Castillo on the hill. Kansas City has shown pop, but Seattle’s bullpen and late-game execution are more trustworthy. Expect a close game, but the Mariners’ edge in power and relief pitching tips the balance their way.

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