Kansas City Royals vs Seattle Mariners Prediction, Odds and Picks for Monday, 06/30/25

The Kansas City Royals head to the Pacific Northwest looking to snap back into form as they meet the Seattle Mariners on Monday in the opener of a four-game set. These teams met at Kauffman Stadium earlier in June, with the Royals taking 2 of 3 games. The Mariners won the only start with RHP George Kirby on the mound, a 6-5 victory on June 9 in the series finale. Kansas City piled up 23 runs in the 3-game set, while Seattle managed to plate 19 runs, and all 3 games in the set ended up going Over.

While that’s all well and good, the Royals have had a lot of trouble plating runs lately. They’ve scored 4 or fewer runs in 7 of the past 8 games, and it’s no surprise the Under is 7-1 in that span. The lone exception was a 9-5 upset of the Los Angeles Dodgers on Saturday as moderate underdogs. For the Mariners, they’ve been a bit of a Jekyll and Hyde team, scoring in bunches, or very few runs at all, with little in between. In Kirby’s last outing, they were on the short end of a 2-0 loss in Minnesota. The Over is 2-1 in his past 3 starts, however, while going 8-2 in the past 10 games overall for the team since June 10. Based on the results of last season, and Seattle’s recent trends, we’ll lean Over, but proceed with caution.

Royals vs Mariners prediction: Over 7.5 (+105) available at time of publishing. Playable to -110.

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