The decision allowed Penny to work on offspeed pitches while providing fifth starter candidate Hong-Chih Kuo his first start of the spring.
Penny threw 72 pitches, more than half of them either split-finger fastballs or curveballs.
"I got a lot of work in," said Penny, who has been urged by the staff to use his split again after abandoning it the second half of last season. "The wind was tough on the curveball, but I was happier with the split."
Penny, the All-Star Game starter last year, tailed off badly in the second half of the season and has had a rough spring as he's tried to expand his repertoire. He has a 12.86 ERA in seven innings with 17 hits allowed and six walks.
Some pitchers shy away from pitching to Minor League hitters because their unpredictability makes pitch sequences difficult, but Penny said he'd prefer a setting like Friday's if he's working on something special.
"If you want to use a pitch in a hitter's count that you wouldn't use in a game, you're not under the microscope this way," Penny said. "This way, it doesn't matter what happens, you can do anything you want. Honestly, I enjoy getting the work in like this. When you try to do this in a game and you run up pitch counts, then they need seven guys out of the 'pen. This way, we can control it."
Penny was up and down for five innings. Pitching coach Rick Honeycutt said Penny started slowly, but finished his final three innings strong. He said one goal is to make Penny's release point uniform for all of his pitches. Otherwise, he tips pitches to hitters and his command is impacted.
"That would be a tip-off to a hitter, if it changes between different pitches," Honeycutt said. "He tends to slow down his delivery for a changeup, so we try to repeat everything the same no matter which pitch it is.
"Early last season, the splitter and fastball, his delivery was closer to being the same, but he went away from the splitter and went toward the changeup. I still feel his changeup can be a competitive pitch. The whole process is to get more offspeed pitches over so hitters can't sit dead-red all the time."
Honeycutt said Penny's next outing will be back in a game.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.