Cahill allowed four runs over two innings. He hit two batters and allowed a pair of hits.
"I'm not putting a lot into the results early," Towers said. "I'd be more concerned if there's similar results a month from now. He was erratic, similar to what we've seen. I didn't think just by sending him down all of a sudden he was going to start pounding the zone."
Cahill will start Tuesday for Triple-A Reno. Pitching guru Dave Duncan is expected to spend time with Cahill, and the team had its mental performance coach, Peter Crone, meet with Cahill as well.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.