"You're always concerned, and we're concerned when something like that happens to our pitcher," Angels manager Mike Scioscia said after an 8-1 win over the Mariners that clinched a postseason berth. "Sometimes it's a cramp and these guys bounce right back, and sometimes there's issues with an oblique that keep guys out for a long time. We don't know what the range is right now."
Shoemaker shut out the Mariners through the first seven innings, then allowed his first run when Humberto Quintero hit an RBI groundout up the middle, scoring Logan Morrison. After the play, Shoemaker -- at 96 pitches and nearing the end of his outing anyway -- was trying to loosen up his left side, drawing the attention of the Angels' medical department and prompting his removal.
The Angels have already lost Tyler Skaggs to Tommy John surgery and watched Garrett Richards suffer a season-ending knee injury on Aug. 20, and they need a committee of relievers every five days because they don't have enough starting-pitching depth.
Watching Angels trainer Adam Nevala check on the 27-year-old Shoemaker, who improved to 16-4 with a 3.04 ERA, was the last image they needed to see.
"Lot of things go through your mind," center fielder Mike Trout said. "He's been big for us this year. I talked to him. It's nothing too serious, I hope. He pitched great. Seeing the trainer go out there, you hope it's something small."
Shoemaker, who tweaked his side throwing a couple of sliders to his final hitter, seemed to believe that was the case postgame and figured it was probably caused from the unusual heat (game-time temperature was 91 degrees).
Asked if he was nervous about Tuesday's MRI, Shoemaker said, "Not necessarily."
Does he think he can start in five days?
"You always plan on doing that," Shoemaker said. "You can't speculate anything right now. We'll find out more tomorrow."
Alden Gonzalez is a reporter for MLB.com. Read his blog, Gonzo and "The Show", and follow him on Twitter @Alden_Gonzalez. This story was not subject to the approval of Major League Baseball or its clubs.