Padres vs Mariners Predictions, Picks & Betting Splits for Sunday Night Baseball

• Seattle starter George Kirby brings a 2.84 ERA into tonight’s Sunday Night Baseball
• San Diego’s Lucas Giolito makes his first start of the season, and first ever for the Padres
• I am targeting under 7.5 runs and SEA moneyline in my Padres vs Mariners picks

The San Diego Padres (27-18, 14-8 away) look to complete a road sweep of the Seattle Mariners (22-25, 12-13 home) on Sunday Night Baseball on May 17. First pitch is scheduled for 7:20 pm PT/4:20 pm ET at T-Mobile Park

With San Diego starter Lucas Giolito making his first start of the season and first in a Padre jersey, oddsmakers have pegged Seattle as the home favorite. I will break down the crucial angles and outline my top wagers.

Padres vs Mariners Predictions & Picks

I am backing the Mariners to end their skid and avoid the sweep. Kirby’s reliable right arm provides a distinct advantage against a likely-rust Giolito.

Moneyline Pick: SEA Mariners (60 cents/-150) at Kalshi

Prediction Markets

SD vs SEA ML Pick

Learn more about Prediction Markets

Kalshi

Seattle

60%

Predict

San Diego hands the ball to veteran right-hander Lucas Giolito. He is tasked with taming a Seattle lineup sitting below the league average in most offensive categories but which is projected to improve; the M’s remain roughly even-money favorites to win the AL West in the MLB division odds. His main challenge will simply be keeping pace with the efficiency expected from his counterpart.

Kirby operates as a foundational piece of the starting rotation. Boasting a 5-2 record, he pairs an excellent 2.84 ERA with a pristine 1.16 WHIP. Under the hood, his 3.24 FIP indicates his run prevention is no fluke.

In his first nine starts of 2026, Kirby is averaging 6.33 innings per game. He relies heavily on pounding the strike zone, walking just 2.21 batters per nine innings while limiting hard contact. If he maintains this pinpoint control, he is well-positioned to stymie the Padre offense.

Game-Total Pick: Under 7.5 Runs (52 cents/-108) at Kalshi

Prediction Markets

SD vs SEA O/U Pick

Learn more about Prediction Markets

Kalshi

Under 7.5 Runs

52%

Predict

Given the offensive woes on both sides of the diamond, the Under is my smartest play. San Diego’s sluggish .223 team average is mirrored by Seattle hitting just .232 collectively. With Kirby pitching efficiently, I expect a low-scoring, grind-it-out affair.

Starting Pitching Matchup Giolito vs Kirby

Check out SBD’s batter vs pitcher stats to see how each lineup has fared against the opposing starter, both over their careers and in more-recent history.

Padres vs Mariners Team Stats & Betting Trends

Despite an underwhelming 12-13 home record, Seattle’s offense at home consistently out-produces San Diego’s lineup on the road. Seattle boasts a .721 home OPS, comfortably outpacing the Padres sluggish .662 road OPS.

Seattle is also squaring up the baseball with more authority, logging an average exit velocity of 88.8 mph. San Diego hits the ball softer away from Petco Park. On the mound, the Mariners pitching staff has been the more reliable unit, yielding a 3.66 overall team ERA compared to the Padres 4.04 mark.

Looking at recent trends, the Padres thrive when catching plus-money this season. They boast a 12-7 straight-up record (63.2% win percentage) as the betting underdog. Backing low-scoring games has also been lucrative for San Diego, with the Under hitting in 70.0% of their last 10 contests.

Padres vs Mariners Odds

The table above displays the best-available odds at online sportsbooks (but does not include prediction sites like Kalshi and Polymarket).

SEA vs SD Public-Betting Splits

Sunday’s MLB public betting splits market show an interesting divide between the casual public and larger bankrolls, especially on the moneyline. The ticket count heavily favors Seattle, pulling in 62.5% of the betting slips. However, the actual handle tells a slightly different story, with 54.1% of the money flowing toward San Diego.

While this divergence is notable, it falls short of qualifying as a true sharp-vs-public situation.

Bettors are not shying away from Seattle in the runline market. The data shows absolute conviction on the home favorites to win by multiple runs. Seattle commands 73.6% of the runline tickets and a staggering 83.8% of the runline money.

In the totals market, the public confidently expects offensive production. Currently, 63.9% of the tickets and 62.5% of the money back the Over. By taking the Under, I am actively fading the public consensus. I prefer to bank on a low-scoring, pitching-dominated affair given the sub-par team batting averages.

SD vs SEA Injury Reports

Both clubs enter this contest battling significant injury woes that directly impact their lineups. For Seattle, offensive injuries are particularly concerning. Catching depth is in a dire state with primary backstop Cal Raleigh on the 10-day injured list. Veteran Mitch Garver is dealing with a back issue that forced him out yesterday.

Missing these bats further restricts a Seattle offense already hitting just .232 on the season. Because the lineup is depleted, there is added pressure on Kirby to dominate. Furthermore, the absence of high-leverage reliever Matt Brash means Kirby is strongly incentivized to pitch deep into the game.

San Diego deals with its own critical absences. Losing starting infielder Jake Cronenworth and catcher Luis Campusano removes key cogs from an inconsistent road lineup. However, their most glaring issues reside on the mound, with their starting rotation decimated.