The 21-year-old pitcher lasted only three innings in a 4-0 loss to the Cincinnati Reds on Tuesday night. He walked five, threw two wild pitches and had an errant pickoff throw. The Reds also stole two bases off him.
Bauer was the first of the 2011 amateur draft picks to reach the majors. He went 1-2 in four starts before being optioned back to Triple-A Reno on Wednesday.
"You can't replace experience," manager Kirk Gibson said. "He doesn't have a lot of it. This is a different game for him. They stole off him last night. He threw some wild pitches. I could chalk it up to he needs more seasoning.
"He understands that he has a lot to work on."
The Diamondbacks called up right-hander Jonathan Albaladejo from Reno. Albaladejo was 3-1 with a 3.34 ERA and 17 saves. He appeared in two games for the Diamondbacks earlier in the season.