Mariners at Diamondbacks odds, picks and predictions

The Seattle Mariners (33-31) and the Arizona Diamondbacks (31-34) open a 3-game series at Chase Field in Phoenix Monday. First pitch is scheduled for 9:40 p.m. ET (FS1). Let’s analyze BetMGM Sportsbook’s MLB odds around the Mariners vs. Diamondbacks odds and make our expert MLB picks and predictions for the best bets.

Season series: First meeting; Mariners won 2-1 in 2024

The Mariners picked up a 3-2 win as -119 road favorites vs. the Los Angeles Angels Sunday, avoiding a 3-game sweep. The victory halted a 5-game skid, too. It was even more surprising given the fact MLB-home run leader C Cal Raleigh (26 HRs) was given the day off.

The Diamondbacks were swept in 3 at Cincinnati as they were outscored 21-6. That certainly splashed cold water on the D-backs after they swept the Braves in Atlanta Tuesday through Thursday. The Under and Over have alternated in each of the past 8 games for Arizona.

In Sunday’s 4-2 loss as a -116 favorite, Arizona 3B Eugenio Suarez went 1-for-4 with a solo home run, his 18th of the season and second in 2 games, while RF Corbin Carroll had went 1-for-3 with a walk and an RBI from the leadoff spot — his RBI single gave the Diamondbacks a 2-0 lead in the top of the third.

Mariners at Diamondbacks projected starters

RHP Emerson Hancock vs. RHP Merrill Kelly

Hancock (2-2, 5.19 ERA) makes his 11th start. He has a 1.47 WHIP, 3.0 BB/9 and 6.8 K/9 in 50 1/3 innings.

• Last start: No-decision, 5 2/3 IP, 1 ER, 2 H (1 solo HR), 2 BB, 6 K in 3-2 home loss vs. Baltimore Orioles Wednesday
• 2025 road stats: 2-0, 3.25 ERA (27 2/3 IP, 10 ER), 3 HR, 5 BB, 19 K, 1.23 WHIP in 5 starts
• Career vs. Diamondbacks: 1 start, win, 6 IP, 1 ER, 2 H (1 solo HR), 2 BB, 4 K in 6-1 home victory April 26, 2024

Kelly (6-2, 3.43 ERA) makes his 14th start. He has a 0.99 WHIP, 2.3 BB/9 and 8.5 K/9 in 76 innings.

• Last start: Win, 7 IP, 0 ER, 1 H, 1 BB, 8 K in 2-1 victory at Braves Wednesday
• 2025 home stats: 3-1, 3.03 ERA (35 2/3 IP, 12 ER), 5 HR, 12 BB, 32 K, 0.98 WHIP in 6 starts
• Career vs. Mariners: 1 start, loss, 5 IP, 3 ER, 7 H (1 solo HR), 2 BB, 6 K in 4-0 home setback July 30, 2023

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Mariners at Diamondbacks odds

Provided by BetMGM Sportsbook; access USA TODAY Sports Scores and Sports Betting Odds hub for a full list. Lines last updated at 4:20 p.m. ET.

• Moneyline (ML): Mariners +140 (bet $100 to win $140) | Diamondbacks -170 (bet $170 to win $100)
• Run line (RL)/Against the spread (ATS): Mariners +1.5 (-150) | Diamondbacks -1.5 (+125)
• Over/Under (O/U): 9.5 (O: -102 | U: -118)

Mariners at Diamondbacks picks and predictions

Prediction

Diamondbacks 5, Mariners 2

The DIAMONDBACKS (-170) are a solid play as moderate favorites behind Kelly at home. Hancock has struggled on the road at times, although he has shown some improvement lately. He has allowed 2 or more walks in 6 of the past 8 starts, and control issues are what does him in. Hancock also has allowed 6 homers in the past 5 starts, too. Back Kelly, who is a little more consistent, especially at Chase Field.

If you’re a little more on the adventurous side, Arizona -1.5 (+125) is worth a look at plus-money. There is plenty of risk as the D-backs just were swept at Cincinnati in 3. Plus, their last 2 victories were only 1-run games. Arizona is 1-7 ATS in its last 8 games as a favorite, and all 7 non-covers were outright losses.

UNDER 9.5 (-118) might be the best play on the board in this interleague series.

The Under is 4-1-2 in the past 7 games for the Mariners, and the Under is at 3-1 clip in the past 4 starts by Hancock.

For the Diamondbacks, there is some risk, as the Under and Over have alternated in each of the past 8 games, with the total going low Sunday in Cincinnati.

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