The Seattle Mariners (53-51) and Arizona Diamondbacks (56-49) wrap up their 3-game series in Phoenix Sunday. First pitch from Chase Field is slated for 4:10 p.m. ET. Let’s analyze BetMGM Sportsbook’s lines around the Mariners vs. Diamondbacks odds and make our expert MLB picks and predictions for the best bets.
Season series: Tied 1-1
Seattle lost 4-3 on Saturday and are 2-3 on their 6-game road trip. The Mariners have averaged nearly 6 runs per game (RPG) over that span. They are 17-17 against the National League on the season.
The Diamondbacks moved to 2-3 on their 6-game homestand. Despite the win, Arizona has struggled to stop their opponents from scoring, allowing 6 RPG over this stretch. They are 28-27 at Chase Field.
Mariners at Diamondbacks projected starters
RHP Luis Castillo vs. RHP Merrill Kelly
Castillo (6-7, 3.02 ERA) will make his 22nd start. He has a 1.04 WHIP, 2.3 BB/9 and 10.2 K/9 in 125 1/3 innings.
- Last start: No-decision, 7 IP, 2 ER, 4 H, 2 BB, 9 K in a 4-3 loss at the Minnesota Twins Monday
- Last start vs Diamondbacks: No-decision, 7 IP, 3 ER, 4 H, 2 BB, 6 K in a 7-4 road loss on June 15, 2022 (as a member of the Cincinnati Reds)
- 2023 away splits: 1-4, 3.38 ERA (48 IP, 18 ER), .231 OBA in 8 games.
Kelly (9-4, 3.12 ERA) will make his 18th start. He has a 1.13 WHIP, 3.5 BB/9 and 9.2 K/9 in 101 innings.
- Last start: No-decision, 6 IP, 1 ER, 4 H, 2 BB, 5 K in a 3-1 loss vs. St. Louis Cardinals Tuesday
- Has never started against the Mariners
- 2023 home splits: 3-3, 3.44 ERA (55 IP, 21 ER), .178 OBA in 9 starts
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 11:45 p.m. ET.
- Moneyline (ML): Mariners -120 (bet $120 to win $100) | Diamondbacks +100 (bet $100 to win $100)
- Run line (RL)/Against the spread (ATS): Mariners -1.5 (+140) | Diamondbacks +1.5 (-165)
- Over/Under (O/U): 8.5 (O: -105 | U: -115)
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Mariners at Diamondbacks picks and predictions
Prediction
Diamondbacks 4, Mariners 3
Moneyline
BET THE DIAMONDBACKS (+100).
I like the Diamondbacks to win just their 2nd series since the All-Star break on Sunday. Seattle is 2-3 on this road trip and 2-games under .500 away from T-Mobile Park on the season.
Castillo has struggled in July, winning just 1 game in his 5 starts this month. Kelly has a 2.51 ERA over his last 4 home starts.
Run line/Against the spread
PASS.
Of course, I would like the Diamondbacks getting the run and a half but not at -165. I also don’t think the Mariners win this game by 2 runs. I’d rather look at the total in this game.
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Over/Under
BET UNDER 8.5 (-115).
Both games in this series have been under so far and you’ve got the best pitching matchup of the series. This feels like it’s going to be a pitching duel. Both of these starters have allowed over 3 ER just once in each of their last 9 starts.
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