"He's gotten real good reports," Gibson said. "I haven't been able to watch him."
McCarthy, who threw a simulated game Sunday, was placed on the disabled list with shoulder inflammation June 1. It marked his second injury stint due to a shoulder issue in as many seasons.
He is 2-4 with a 5.00 ERA in 11 starts with the D-backs this season.
Andrew Owens is an associate reporter for MLB.com. Follow him on Twitter @OwensAndrew. This story was not subject to the approval of Major League Baseball or its clubs.