The Seattle Mariners (83-69) will look to rebound after a 7-5 loss to the Kansas City Royals (76-76) in the second game of their three-game series. Thursday’s matchup at Kauffman Stadium features a high-quality pitching matchup between Seattle’s Luis Castillo and Kansas City’s Stephen Kolek. Both teams are still alive in the playoff race and will look for a big win here. Continue reading to get my Mariners vs Royals prediction for Thursday afternoon.
Our Mariners vs Royals Pick
- Pick: Mariners Moneyline
- Confidence: 3/5
- Get Your Bonus Bets: Use bet365 bonus code ATSBONUS to bet $5 and get $200 in bonus bets for this game!
Game Snapshot
- Matchup: Seattle Mariners vs Kansas City Royals
- Date & Time: Thursday, September 18, 2025, 2:10 PM ET
- Starting Pitchers: Luis Castillo (SEA) vs. Stephen Kolek (KC)
- Stadium: Kauffman Stadium, Kansas City, MO
- Broadcast: ROOT Sports NW, FDSKC
Key Storylines
- Pitching matchup: Luis Castillo (9-8, 3.76 ERA) aims to lead the Mariners back to victory in this game. Castillo started the month of September by giving up five runs to the Tampa Bay Rays. He has bounced back nicely since then, giving up a total of two earned runs over 12 innings in his last two starts. Kansas City’s Stephen Kolek (5-5, 3.71 ERA) seeks to continue his strong performance for the Royals. Since joining Kansas City from the San Diego Padres, Kolek has allowed a total of four earned runs in 19.2 innings of work.
- Key Players: Mariners catcher Cal Raleigh is up to 56 home runs and 118 RBI this season. He has set a new MLB single-season record for a switch-hitter. He is joined by another elite power bat in Eugenio Suarez in the Seattle lineup. Royals star Bobby Witt Jr. leads the team with a .293 batting average. Vinnie Pasquantino leads the Royals with 30 home runs and 104 RBI.
- Recent team streaks: The Mariners had a 10-game winning streak snapped by the Royals on Wednesday. Kansas City has won two of its last three games and needs to keep winning to keep their slim Wild Card hopes alive.
Best Player Props
| Player | Prop |
|---|---|
| Cal Raleigh | Over 0.5 Home Runs |
| Bobby Witt Jr. | Over 0.5 Home Runs |
| Stephen Kolek | Under 5.5 Strikeouts |
Betting Trends & H2H
- The regular season series between the Mariners and Royals is tied 3-3.
- This is the final game of the season series between Seattle and Kansas City.
- The over has cashed in two straight meetings between these two teams.
Mariners vs Royals Model Projection
- Score Projection: Mariners 5 – Royals 3
- Win Probability: Mariners 60%, Royals 40%
Final Thoughts
I give the Mariners the edge in this matchup with the Royals on Thursday afternoon. Seattle has a starting pitching advantage in this game with Luis Castillo on the mound. They also have a more explosive offense, with the duo of Raleigh and Suarez presenting a constant threat against Royals pitching. I’ll take Seattle to win this game on the moneyline and for Seattle to put pressure on the Astros in the AL West race.
