Diamondbacks vs. Giants Prediction, Odds, Probable Pitchers and Prop Bets for Monday, May 12

Can the D-Backs improve to 5-4 in Merrill Kelly's starts this season?

The Diamondbacks are road favorites on Monday. / Rick Scuteri-Imagn Images

The Arizona Diamondbacks are just one game over .500 this season, but they are favored on the road against the San Francisco Giants in their season opener on Monday night.

San Francisco is three games up on the Diamondbacks in the NL West standings, but veteran Justin Verlander (4.50 ERA) is on the mound for the Giants in this one. San Fran has struggled in his starts, going 3-5 straight up despite the former Cy Young award winner settling in after a slow start to 2025.

Verlander will take on an Arizona offense that ranks in the top five in MLB in OPS this season. The D-Backs will counter with Merrill Kelly (4.09 ERA) on the mound for his ninth start of the 2025 campaign.

Here’s a breakdown of the odds, players to watch in the prop market, and my prediction for Monday’s matchup.  

Diamondbacks vs. Giants Odds, Run Line and Total

Odds via DraftKings Sportsbook.

Run Line

• Diamondbacks -1.5 (+142)
• Giants +1.5 (-170)

Moneyline

• Diamondbacks: -118
• Giants: -102

Total

• 8 (Over -110/Under -110)

Diamondbacks vs. Giants Probable Pitchers

• Arizona: Merrill Kelly (3-2, 4.09 ERA)
• San Francisco: Justin Verlander (0-2, 4.50 ERA)

Diamondbacks vs. Giants How to Watch

• Date: Monday, May 12
• Time: 9:45 p.m. EST
• Venue: Oracle Park
• How to Watch (TV): FS1
• Diamondbacks record: 21-20
• Giants record: 24-17

Diamondbacks vs. Giants Best MLB Prop Bets

Diamondbacks Best MLB Prop Bet

• Josh Naylor to Hit a Home Run (+650)

Looking for a fun prop angle in this matchup? I shared in today’s Daily Dinger – our daily home run picks here at SI Betting – why Naylor is worth a look against the Giants: 

This last pick is a bit of a dart throw, but I’m looking to fade San Francisco Giants starter Justin Verlander on Monday.

Verlander has given up six homers in eight appearances this season, posting a 4.50 ERA. Now, he’s taking on an Arizona Diamondbacks squad that is in the top five in MLB in OPS this season.

While I toyed with the idea of backing Corbin Carroll, Eugenio Suarez or Ketel Marte with this pick, but all three players have shaky stats against Verlander in his career.

Enter Josh Naylor.

While Naylor hasn’t been great against Verlander, he is 3-for-11 with a .545 OPS. This season, the lefty is hitting an impressive .293 with four home runs. I think bettors could do much worse than backing Naylor at +650 to go deep tonight. 

Diamondbacks vs. Giants Prediction and Pick

While Verlander has settled in after a slow start to the season, so has Kelly. In fact, Kelly had one bad outing where he allowed nine runs, but other than that has been great for Arizona.

In eight starts, Kelly has seven with three or fewer runs allowed, and he’s posted a 2.57 ERA in six starts since the nine-run outing on April 3. That puts the D-Backs in a solid position on Monday since their offense has been so great this season.

Arizona ranks in the top five in MLB in OPS, runs scored, and home runs, while the Giants are just 20th in OPS, 11th in runs scored, and 25th in batting average in 2025.

In a fairly even pitching matchup – Verlander has been a lot better over his last four starts – I lean with the superior offense in this game. San Francisco does have the top bullpen ERA in the league, but I don’t think it’ll be in the lead when Verlander exits on Monday evening. 

Pick: Diamondbacks Moneyline (-118 at DraftKings)

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Odds refresh periodically and are subject to change.

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