DENVER — A demotion is never palatable, especially not after allowing eight runs in four innings, and that is what upset Jonathan Pettibone the most.

"You want to leave a lasting impression, so they know who they want to call back up when someone is needed," Pettibone said. "It's frustrating. But I'll go down there, get after it and get better."

Pettibone was optioned to triple-A Lehigh Valley after Friday's 12-1 loss. Veteran reliever Shawn Camp's contract was purchased and added to the 40-man roster. That was a "predetermined" roster move, Phillies manager Ryne Sandberg said, and it did not matter how well Pettibone fared.

He was a temporary placeholder for Cole Hamels, who will start Wednesday in Los Angeles. This way, the Phillies can carry eight relievers for the next four games until Hamels is activated.

"We were going to have to do that," Sandberg said. "Pettibone is going to go work and get reps in and work on some things."

The 23-year-old righthander's second impression was not as favorable as his 18-start rookie season that yeilded a 4.04 ERA. He was the team's best candidate for the fifth starter's spot in the spring before soreness in his right shoulder recurred. That provided a chance for David Buchanan, who dazzled in the spring. He may have leapfrogged Pettibone on the organizational depth chart.

Pettibone must prove himself again in the minors.

"It's something I can learn from," Pettibone said. "I can take it into triple A, build off it, get better and get back up here."

Camp will be available Saturday. The 38-year-old righthander led the majors in appearances with Chicago in 2012 but sputtered to a 7.05 ERA in 26 games last season. He, too, was solid in the spring.

His addition puts the 40-man roster at 40. It is unlikely the Phillies would summon Camp for four days just to designate him for assignment, so either B.J. Rosenberg or Jeff Manship could be squeezed from the roster to clear space for Hamels. Rosenberg has an option remaining; Manship does not.

Both righthanders permitted runs in the later innings of Friday's rout.

Have a question? Send it to Matt Gelb's Mailbag.