Two days after joining the Padres in Seattle to provide short-term bullpen coverage, right-hander Alek Jacob has been optioned back to Triple-A El Paso to make room for right-hander Lucas Giolito, who will get the start for Sunday’s 4:20 p.m. first pitch on NBC/Peacock.

The 27-year-old Jacob appeared in one game — on Saturday, when he allowed two runs on two hits and a walk without recording an out. His previous outing was much better as he struck out three over two shutout innings in a win on April 15.

Jacob had 4.08 ERA, 18 strikeouts and 10 walks in 17⅔ innings so far in the Pacific Coast League.

Giolito discussed finally joining the Padres’ rotation in this story.

The Padres have won all five meetings so far with the Mariners but are shaking up the lineup for the series finale in hopes of getting their big bats clicking.

Sunday night showdown. pic.twitter.com/hUGB38OPD6

— San Diego Padres (@Padres) May 17, 2026

The biggest change: center fielder Jackson Merrill has been dropped from leadoff to sixth, his lowest spot in the order this year.

Merrill is hitting .205/.275.325 with four homers and 18 RBIs in 43 games. He is hitting .067/.176/.067 over his last eight games and was hitting .143/.250/.190 in 11 starts as the leadoff hitter.

The slumping Fernando Tatis Jr. (.586 OPS) will hit leadoff for the first time since April 4 in Boston and will man second base as Ramón Laureano (.684 OPS) gets the start in right field and Gavin Sheets (.804 OPS) gets the start in left field.

Sheets is also getting his first start in the three-hole while Miguel Andujar (.801 OPS) is getting his third start in the two-hole and will man third base a second straight game, which gives Manny Machado (.604 OPS) a second straight DH day.

Shortstop Xander Bogaerts (.746 OPS) will bat fifth, Ty France (.791 OPS) will bat eighth and play first base in his first start of the weekend and Freddy Fermin (.479 OPS) will catch and bat ninth.

Here is how the Mariners will line up for the series finale:

Steelheads Sunday 🔜

📺 NBC, @peacock
📻 @SeattleSports pic.twitter.com/t71KIyEsKj

— Seattle Mariners (@Mariners) May 17, 2026

 

Sunday’s pitching matchup

Padres RHP Lucas Giolito (2026 debut)

He last started for Double-A San Antonio on Sunday. The 31-year-old Giolito had a 4.76 ERA in a four-start build-up in the minors, finishing with six innings of one-run ball (74 pitches) in which he struck out three without a walk. Giolito has a 4.35 ERA in four starts in his career against the Mariners.

Here is how Giolito has fared against current Mariners:

Mariners RHP George Kirby (5-2, 2.84 ERA)

He’s allowed two or fewer runs in seven of his nine starts and he’s struck out 46 batters against 14 walks over 57 innings. Kirby has a 10.38 ERA in two career starts (8⅔ IP) against the Padres, the last in 2024 (5 IP, 5 ER).

Here is how Kirby has fared against current Padres: