"He touched 93 mph, good breaking ball," Gonzalez said. "Threw well. He's going on to his next start."
Sheets, a four-time All-Star, had not pitched since July 19, 2010, when he was a member of the A's. He has since undergone Tommy John surgery and was out of baseball before signing a Minor League contract with the Braves on Sunday.
Gonzalez said Mississippi pitching coach Mike Alvarez said Sheets was "amped up" before his start.
"You can just imagine," Gonzalez said. "The guy hasn't pitched professionally in two years. That's a good sign."
Sheets will make his next start at Double-A on Monday. General manager Frank Wren said the team will re-evaluate Sheets' progress at that point, but it is possible he will be ready to join the Braves when they return from the All-Star break.