"We're going to give him a day and see if he feels better tomorrow," McClendon said.
If Cruz starts Thursday, it'll likely be at designated hitter, the skipper added.
Cruz had felt tightness in his back during Tuesday's batting practice but decided to play through it. In the fifth inning, he whiffed on a 2-1 offering from Indians right-hander Corey Kluber, then fouled off the next pitch. McClendon, noticing his star's visible discomfort with both swings, made an immediate substitution.
A day later, the manager wasn't taking any chances with Cruz, who leads the American League with 18 home runs and boasts a .326/.381/.607 slash line. The 34-year-old is a bright spot on what has otherwise been a disappointing Mariners offense, which entered Wednesday having scored three runs or fewer in 13 straight games.
"Too valuable," McClendon said of Cruz. "I haven't even talked to him [about playing Wednesday]. Don't want to talk to him."
Cruz said he hadn't had back issues at all this season until feeling some tightness during Sunday's game. He went 2-for-4 that afternoon and was 0-for-2 on Tuesday before being removed midway through his third at-bat.
Mark Trumbo, who was acquired in a six-player trade with the Diamondbacks on June 3, made his first appearance at right field for the Mariners on Wednesday. McClendon said the 29-year-old will receive more opportunities in the outfield, allowing the Mariners to DH Cruz in the upcoming days.
"I don't want to push it," Cruz said. "Just gotta be smart with this."
Alejandro Zúñiga is an associate reporter for MLB.com. Follow him on Twitter @ByAZuniga.