The D-backs' third baseman aggravated his jammed right thumb during his seventh-inning at-bat, a popup to second base. Reynolds had four hits in his previous 57 at-bats, shrinking his season batting average to .199.
Arizona interim manager Kirk Gibson said he was unaware of the severity of Reynolds' recurring mishap.
"He wants to play," Gibson said. "I've asked him constantly. He says, 'No, I'm fine.'
"You get to the end of the season, everything starts piling up on you in your whole body."