Seattle Mariners vs Kansas City Royals Prediction, 9/18/2025 MLB Picks, Best Bets & Odds

Game: Seattle Mariners vs Kansas City Royals

Date: Thursday, September 18, 2025

Location: Kauffman Stadium in Kansas City, MO

TV: FanDuel Sports Network Kansas City

Odds/Point Spread: Seattle (-182) Kansas City (+150)

Kauffman Stadium is the site where the Kansas City Royals (75-76) will take on the Seattle Mariners (83-68) on Thursday. The moneyline on this matchup has Seattle at -182 and Kansas City is opening at +150. The over/under is set at 8.5. The expected starting pitchers will be Luis Castillo and Stephen Kolek.

As a team, the Seattle Mariners are scoring 4.8 runs per game, which is 10th in baseball. They have a total of 717 runs and hold an on-base percentage of .321. The Mariners have hit 218 two-baggers as a team and have knocked 221 balls out of the stadium. They have tallied 687 runs batted in and 1,256 base knocks for the season, and their average at the plate sits at .244. Seattle owns a slugging percentage of .419 and have been called out on strikes 1,334 times, while taking a walk on 513 occasions.

Get all of our MLB Expert Picks

The Mariners are sitting with a team ERA of 3.92 for the season (14th in baseball), and the staff has rung up 1,321 batters. Mariners pitchers have given up 181 home runs and 659 total runs (16th in baseball). They have walked 434 players from the other team and their FIP comes in at 4.04 as a unit for the year. Seattle has allowed 1,253 base hits (8.3 per 9 innings) and also 594 earned runs. They have earned a K/BB ratio of 3.04 and their pitching staff has a collective WHIP of 1.24.

The Mariners have dispatched 513 relief pitchers to the hill so far this season. The relief pitchers have inherited 137 runners this season with 25.5% of those players ended up crossing the plate. They have earned 40 saves on the campaign and have blown 24 of their 64 chances to get a save. The Mariners relief pitchers have accumulated a save rate of 62.5% and have come into the game in 149 save situations. The relief pitchers have recorded 85 holds this season (15th in MLB). Mariners relief pitchers have stepped onto the hill with runners on base 126 times in addition to having 205 appearances in high leverage situations.

The San Francisco Giants have a total of 4,094 putouts this year, as well as 1,271 assists and 65 errors. Their fielding percentage is holding steady at .988 which puts them in 7th in the majors, and they have turned 110 double plays. The Mariners have converted 70.2% of baseballs in play into outs out of their 12,282 innings on the field, which ranks them 13th in baseball.

Castillo has pitched in 1,397 frames and is sitting with 1,480 strikeouts in his pro baseball career. Castillo (82-84 career win-loss mark) has earned a FIP of 3.53 while he has faced 5,780 hitters in the major leagues. His earned run average is 3.58 (556 earned runs allowed) and his career WHIP is 1.186. He has given up 1,204 hits (7.8 hits per nine innings) and has 453 walks.

Kansas City has accumulated 146 long balls on the season as well as 572 runs batted in. They have tallied 264 doubles, while taking a walk 400 times and scoring 582 runs. The Kansas City Royals have accumulated a team on-base percentage of .305 as well as a batting average of .244 for the year. The Royals hold a slugging % of .391 and they are earning 3.85 runs per outing (28th in the league). They have been called out on strikes on 1,021 occasions (30th in the league) and have a total of 1,227 base hits.

The Royals are sitting with a team WHIP of 1.258 in addition to having a FIP of 4.05 as a team this year. They rank 14th in the league as a staff in total hits conceded with 1,235. The Kansas City pitching staff have given up 601 runs this season while having an ERA of 3.78 (562 earned runs relinquished). Their K/BB ratio comes in at 7.90 (1,179 strikeouts against 450 bases on balls). They have allowed 160 HR's and they give up 4.04 runs per 9 innings (4th in baseball).

Kansas City has called on bullpen pitchers to take the mound in 63 save opportunities and they have tallied 44 saves. They rank 3rd in baseball holding a save percentage of 69.8%, and they have dispatched 510 relievers to the mound so far this season. Their relief pitchers have stepped onto the hill 161 times in high leverage situations and also on 152 occasions with base runners. Kansas City bullpen pitchers hold an inherited score rate of 26.6% of 207 inherited base runners. With 142 save situations, the Royals have amassed 78 holds and 19 blown saves.

The Kansas City Royals have turned 122 double plays and have a fielding percentage of .989 (5th in the majors). The Royals have recorded 1,336 assists, 58 errors and have 4,017 putouts over the course of the season. Out of their 12,051 innings on the diamond, the Royals hold a defensive efficiency of 70.6% (9th in the majors).

During his career, Kolek has conceded 150 base knocks while he has totaled 106 strikeouts in 145 frames. Kolek (8-5 record in his career) has earned a 4.21 ERA and has allowed 9.3 hits per 9 innings. He has conceded a total of 68 earned runs while holding a WHIP of 1.308 and a FIP of 4.1. He has a K/BB ratio of 2.65 and he has gone up against 621 opposing hitters thus far in his career.

Who will win tonight's MLB game against the spread or moneyline?

Josh Schonwald's Pick: Take Seattle (-182)

Get $60 worth of FREE premium member picks. No Obligation. No Salesman. No Credit Card. Fast Sign up with Instant Access Click Here