Cruz, a Rule 5 Draft pick who throws as hard as 100 mph, appeared in seven games for the Astros and was 1-0 with a 2.08 ERA, with eight strikeouts and four walks in 8 2/3 innings.
"We got to the point we were relying on him quite often," Astros manager Brad Mills said. "We're going to see how he throws tonight and how he throws Monday and see where he is. He might be pretty close. We don't know."
Mills hasn't been shy about using Cruz in tight situations because of his ability to get a key strikeout. While Brett Myers' spot is secure in the bullpen as the closer, Mills said he's typically been using his relievers based on matchups.
"You look at the types of hitters they're going to face and see if there's an advantage," Mills said.