"It was good to see him out there and turning the ball loose," Padres manager Bud Black said. "He was a little rusty and not dotting the ball like he can. But he's healthy."
Maurer has been sidelined for the past week or so with soreness in his back, which wasn't the result of anything he did on the mound in a game or during workouts, he said.
"It was just a little tightness," Maurer said. "It happened during stretch. It locked up and it couldn't get loose."
This isn't the first time Maurer has dealt with back soreness.
While with the Mariners last season, Maurer was sidelined in Spring Training with back and neck pain, which might have prevented him from making the Opening Day roster.
Then in May, after he struggled as a starter, Maurer needed an MRI on his back. He was later optioned to Triple-A Tacoma, where the decision was made to convert him into a full-time reliever.
"I had it a little last year, but this time it took less time [to recover]," he said.
Despite missing 12 days of potential game action, Maurer didn't have any concern about his downtime.
"I've still got plenty of time to get ready," he said.
Before Wednesday, Maurer's only other appearance came on March 6 against the White Sox when he allowed two hits and had one strikeout in his only inning of work.
• After the game, the Padres announced that outfielders Rymer Liriano and Alex Dickerson have been optioned to Triple-A El Paso and that outfielder Rico Noel has been reassigned to Minor League camp.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.