Matt Waldron’s time in the Padres organization is not at an end after all.
The knuckleballer was placed on the 15-day injured list on Friday with a right brachialis muscle injury and replaced by right-hander Alek Jacob for short-term bullpen coverage. Jacob will likely be the odd man out when the Padres need the roster spot to start Lucas Giolito later this weekend in Seattle.
Friday’s first pitch is at 6:40 p.m. on Padres.TV.
Waldron was out of options and could not be sent to the minors without being exposed to waivers, but the Padres avoid having to make that decision after the 29-year-old right-hander came down with an arm injury a day after a surprise appearance out of the bullpen.
The brachialis is a muscle in the upper arm near the biceps.
Surgery on Waldron’s lower half in spring training allowed the Padres to keep him longer than expected, as he was able to be placed on the injured list to start the year and then ramp up on a minor league rehab assignment.
Waldron made his first start on April 17 to replace the injured Nick Pivetta and made three traditional starts before finding success behind an opener on May 6 (5 IP, 1 ER, 7 Ks).
But Waldron allowed six runs in 2⅔ innings behind an opener on Tuesday in Milwaukee. He spared the bullpen some with four strikeouts over two shutout innings on Thursday.
Waldron has an 8.49 ERA in 23⅓ innings this year and a 5.25 ERA in 216 innings in the majors. He had his best stretch while posting a 3.05 ERA over a 16-start stretch in 2024 to help the team win the NL’s top wild-card spot.
Padres manager Craig Stammen said after Thursday’s game that Waldron would be in the bullpen, but he’ll instead be on the injured list.
The 27-year-old Jacob earned the win with two shutout innings against his hometown Mariners on April 15 and was optioned out afterward. That was his only appearance this season.
Jacob was 3-0 with a 4.08 ERA, 18 strikeouts and 10 walks in 17⅔ innings at Triple-A El Paso.
A day after sitting against a left-hander, center fielder Jackson Merrill (.629 OPS) is back in the lineup and atop the order to start a three-game series in Seattle.
New series starts today. pic.twitter.com/NuPx7g3tws
— San Diego Padres (@Padres) May 15, 2026
Fernando Tatis Jr. (.606 OPS) is back in right field after three straight starts at second base, Gavin Sheets (.747 OPS) is at first base, Miguel Andujar (.796 OPS) is the DH and Sung-Mun Song (.544 OPS) will get his first start in the infield since Sunday in San Diego.
Spong is 0-for-9 since going 2-for-4 in his first start in the majors.
Here is how the Mariners (22-23, 2nd in AL West) will line up to start Game 1:
Emerson Hancock bump day 👊 pic.twitter.com/rVUpyIyYl4
— Seattle Mariners (@Mariners) May 15, 2026
Friday’s pitching matchup
Padres RHP Randy Vásquez (4-1, 3.05 ERA)
The Padres are 7-1 in his starts so far, but he hasn’t completed six innings in his last three appearances (5.17 ERA). Vásquez allowed four runs on five hits and four walks in four innings in his start this year against the Mariners, his shortest this season.
Here is how he’s fared against current Padres:
Mariners RHP Emerson Hancock (3-1, 3.21 ERA)
Five of his eight starts have been quality but he allowed five runs in six innings in his last start, a win, at the white Sox. Hancock limited the Padres to two runs on four hits and a walk in six innings at Petco Park last month. He struck out six.
Here is how Hancock has fared against current Padres:
