Walston (elbow) struck out five and allowed two hits and no walks over 3.2 innings in a rehab start for Triple-A Reno on Sunday.
According to Jesse Friedman of GoPHNX.com, manager Torey Lovullo said July 26 that the Diamondbacks were undecided on what Walston's role might look like upon the left-hander's return from the 15-day injured list, but Walston's usage Sunday implies that he'll be built back up as a starter. With Eduardo Rodriguez and Merrill Kelly both beating him back from the IL, the Diamondbacks don't have a rotation spot available for Walston at the moment, though the complexion of Arizona's pitching staff could change by the time Walston is ready for activation. Walston posted a 2.84 ERA and 11:9 K:BB across 12.2 innings in three outings (two starts) for Arizona before landing on the IL on June 6 with a left elbow strain.