The concern about Wang has been growing ever since he was removed from the rotation and demoted to the bullpen at the end of June. He fared no better as a reliever, allowing six earned runs and eight hits over just three innings of work out of the 'pen.
Manager Davey Johnson reiterated his worries about Wang's inefficiency on Tuesday evening and said things came to a head when Wang threw a session before the game.
"Chien-Ming threw a 'pen and then he complained of something in his hip, and he was examined by our doctors and they said it was a hip strain," Johnson said.
Rodriguez, who is returning from a strained right index finger, threw one-third of an inning late on Tuesday night, recording the final out of the game with a strikeout in the ninth.
He is 1-3 with a 5.06 ERA and nine saves this year, through 25 games.