"He's on the shelf," D-backs manager Kirk Gibson said. "It's a setback. He's not ready. We'll bring him back here, keep his arm going and get the calf healed. It's not healed now."
Saito threw a scoreless inning on Thursday at Class A Visalia, giving the D-backs hope he would soon be ready to pitch for the big league club. Now he will come back Phoenix to work up the injured calf again.
The 42-year-old had a 2.03 ERA in 20 relief appearances for the Brewers last year.