Shortstop Brendan Ryan and outfielder Casper Wells did not make the team's trip to Cleveland, instead remaining in Seattle to receive MRIs on their respective ailments.
Ryan is sidelined with tightness in his upper back and neck, and left Tuesday's game against the Yankees. He returned to play a full game on Friday, but exited Saturday's loss to Texas in the third inning.
Wells was scratched shortly before Saturday's contest against the Rangers after feeling ill. He has just three hits in his last 45 at-bats.
"Wells has something going on with his head," manager Eric Wedge said. "We're just trying to figure out what that is."
Wedge said that infielder Chone Figgins, out for the season with a hip flexor injury, would also receive additional medical attention this week.
"We're just trying to get to the bottom of everything," Wedge said, "and make sure that when we do get into the offseason, we have as much information as we need so that everyone is going to come in healthy next year."