James Paxton was torched for nine runs -- eight earned -- in 2 2/3 innings by the Blue Jays on Monday.
Roenis Elias will need 4-6 weeks of rehab after an MRI revealed a strained left flexor bundle in his elbow.
Chris Young has been moved to the Mariners' bullpen.
Michael Saunders went 2-for-3 with a two-run home run and two runs scored in Sunday's loss to the Astros.
Hisashi Iwakuma lost his third straight start Sunday, allowing four runs over 4 1/3 innings against the Astros.
Roenis Elias (elbow) could pitch in relief during the final week if his MRI results come back clean.
Chris Young allowed seven runs on eight hits in just three innings in the Mariners' 10-1 loss to the Astros on Saturday.
Taijuan Walker allowed two runs over 5 2/3 innings Friday in a 10-5 win over the Astros.
Dustin Ackley had big night at the plate Friday against the Astros, going 2-for-4 with two solo home runs, a walk, and three runs scored.
Kyle Seager finished 2-for-5 with a three-run home run in Friday's win over the Astros.
Mike Zunino was 2-for-5 with a three-run homer against the Astros on Friday.
Roenis Elias' left elbow injury is not considered serious.
Fernando Rodney allowed one run in the ninth inning against the Angels on Thursday but hung on to earn his 46th save of the season.
Logan Morrison blasted a game-winning three-run homer in the top of the ninth inning to break a 0-0 tie and push the Mariners to a 3-1 win over the Angels on Thursday.
Felix Hernandez fired seven shutout innings, striking out 11, in a no-decision against the Angels on Thursday.