Marshall likely would not have been available Monday and Wagner could have been out two or three days after throwing 60 pitches Sunday.
"We just needed some arms," manager Chip Hale said. "We've told Marshall and Wagner both, hey, this isn't because you're not pitching well. You may have had a rough spot here but it has nothing to do with that. It's about availability today and even maybe [Tuesday] with both of them and needing arms."
Hessler had a 5.06 ERA in seven appearances at Mobile, while Leone had a 3.86 ERA in six relief appearances at Reno.
Steve Gilbert has covered the D-backs for MLB.com since 2001. Follow him
on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.