Saunders had been on the disabled list since June 23 with tightness in his left shoulder.
A starter throughout his time in the Minors and during his first stint this year with the D-backs, Corbin had been pitching out of the bullpen. With a stretch of 20 games in 20 days, and after watching his starters not pitch deep into games, manager Kirk Gibson needs relievers that can pitch on consecutive days.
Given that Corbin has never done that in his career, the team did not want to have him do that now.
"I guess, ultimately, we weren't very comfortable asking him to do that yet," Gibson said.
In addition, by returning to Reno, Corbin will be able to start again and continue to build up his innings.
Corbin said he understood the move and was thankful to have gotten another taste of the big leagues.
"He's done a phenomenal job," Gibson said. "We really like the kid a lot. He's got a great future."