Heisey's barely got over the left-center-field wall.
"I think that last one -- I didn't think that was going to go, honestly. I thought it was a routine popup," Shields said. "I thought the other two were homers for sure. They put some good swings on it today."
Shields, who had given up just one earned run in his previous 14 2/3 innings, will use his final Arizona start as a lighter tuneup for March 31 at Detroit. Against the Reds, he went six innings with 97 pitches.
"I feel great, my body feels good. It's nice to go 100 pitches, and I felt good from the first pitch to the last pitch today. That's really my main focus right now," Shields said. "We're going to try to tone it up with this next start, maybe 60 pitches or so, and then get ready for the season."
Manager Ned Yost was just happy that Shields got his work in.
"He reached all the objectives we wanted him to reach. He got to the 100-pitch mark, right on it, and that was good," Yost said. "I'm glad that most of his starts have been pretty easy for him. He got a good workout today, so I was pleased with that. He's ready to go."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.