Seattle Mariners vs. Kansas City Royals Picks and Prediction, Tuesday, September 16, 2025
Use Code WWWC The Seattle Mariners (82-68) and the Kansas City Royals (75-75) start up a three game series on Tuesday in the American League in this Mariners vs. Royals prediction. These teams each had the day off on Monday. These teams played a four game series in early July, splitting the wins in Seattle. The Mariners will start Logan Gilbert (3.54 ERA) and the Royals are going with Michael Wacha (3.45 ERA). First pitch is set for 7:40 EST. Keep reading to see our Mariners vs. Royals prediction, and check out all of our best Free MLB Picks.
Seattle Holds Narrow Lead
The 2025 MLB regular season is nearing a close, but there is still plenty to be figured out in the AL West, and the entire American League in general. The Houston Astros led their division for most of the second half of the season, but the Seattle Mariners recently stormed back and have taken over the top spot by just one game. How did they do this? Well, Seattle is on a nine game win streak as they head into this series with the Royals, and look to keep this momentum going to lock up their spot in the postseason.
The Mariners are coming off a four-game sweep against the Angels, winning the final game 11-2 on Sunday at home. Cal Raleigh just tied Mickey Mantle's record for most home runs by a switch-hitter with 54 on the year. Raleigh is leading the Majors in home runs and is third in RBIs with his 115 on the season. He bats .244 on the year, and took the second spot in the lineup on Sunday while taking his usual spot as the catcher. Julio Rodriguez batted behind him as their centerfielder, he has a strong 30 home runs and 91 RBIs with the best batting average among qualified batters on the team at .269.
Logan Gilbert will make his 23rd start of the season as a 28-year old right hander. He has a 4-6 record, the the team going 2-3 overall in his last five starts. His ERA is 3.54 to go with 159 strikeouts against 28 walks. In his last start, Gilbert gave up one run in 4.2 innings in a win over the Cardinals.
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Royals Need a Miracle
The Kansas City Royals are technically still alive in the playoff hunt at the time of publishing, but they are likely running out of time and will eventually be eliminated as they watch the playoffs from home. Kansas City is six games out of the final Wild Card spot with 12 games to go. They are not just battling with one team either, as the Red Sox, Rangers, Astros, and Guardians are all competing for the final two Wild Card spots behind the Yankees.
The Royals just lost two of three on the road against Philadelphia, but were able to steal the last game with a strong 10-3 win, preventing the Phillies from clinching their playoff berth. Salvador Perez had a big game on Sunday. He went for two hits and five RBIs, including his three-run home run in the sixth inning. Perez is now 35 years old, but still has some pop in his bat as he is up to 28 home runs and 89 RBIs on the season. Their top power hitter has been Vinnie Pasquantino; he has 30 home runs and 104 RBIs, leading the team in both categories.
Michael Wacha makes his 29th start of the season as a 34-year-old right-hander. This will be his first game back after serving a seven day stay on the IL with a concussion. His record is 9-11 to go with a 3.45 ERA. In his last start, Wacha gave up one run in 5.2 innings in a win over Minnesota.
Mariners vs. Royals picks and predictions
Moneyline Pick for Mariners vs. Royals
- Mariners -135 (5 units)
Three reasons to take Seattle in this game: motivation, momentum, and pitching. First, Seattle is in a tight battle for the top of the AL West as they are only one game ahead of the Astros. More importantly, the second-place team in the AL West is not guaranteed a Wild Card spot, due to other strong teams in the AL. Seattle needs this win, and they are also hot as they have won all of their last nine coming into this matchup. The Royals have lost three of their last four, never got the full impact they were expecting from Bobby Witt Jr., and can only be so motivated to spoil other teams' playoff hopes. Wacha is making his first start back after a concussion, not a great spot to back Kansas City. Seattle wins here.
Take the Mariners to win.
Over/Under Pick for Mariners vs. Royals
- Under 8.5 (4 units)
Days off in baseball can sometimes be misleading. A popular thought is that it allows the batters to rest and regain strength, but it is actually far more important for the bullpen. The batters are used to swinging every day, but the pitchers in the bullpen will be at full strength, which will impact this game. The starters in this game are solid, as both Gilbert and Wacha have ERAs under 4.00. The Royals just had a high-scoring game against Philly, and will likely crash back down to their average. Seattle can win low-scoring games, as three of their last five wins went under the total.
Take the under.
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