PHILADELPHIA—Maybe it’s a cautious optimism. Maybe they’re not all that thrilled.

Ask GM Ruben Amaro, manager Charlie Manuel and pitching coach Rich Dubee why they’ve tapped Jonathan Pettibone to replace John Lannan in the rotation tomorrow in the series opener against the Pirates, and they’ll tell you that it just worked out that way.

“I think it lined up well for him,” Amaro said on Sunday, before the series finale against the Cardinals tonight. Pettibone’s next scheduled turn, as it happened, is Monday.

Dubee said he first found out about Pettibone when reporters asked about him.

“That’s fine,” said Manuel, when asked about the move. “You know, I mean, he’s young and he’s definitely got a future ahead of him. And we’ve got to have somebody pitch.”

Which they will, according to medical reports from team doctors, for 6-8 weeks while Lannan nurses a left quad strain back to health. Maybe longer. Who knows.

“I think it’s the way the rotation was going and evidently what they thought,” Manuel said later. “I mean, he was in line to pitch tomorrow, so that’s who we kinda brought up.”

So the stars aligned, and Pettibone gets the ball tomorrow.

One possible reason for the reservation: Pettibone has an ERA north of 10.00 in Triple-A so far, after serving six runs on eight hits in just 5 1/3 innings in his 2013 debut in Syracuse (Nationals affiliate), and four runs in four innings in his follow up last Tuesday.

Amaro said Pettibone’s reportedly throwing in the 91-94 m.p.h. range, though he also said his minor league eyes tell him Pettibone’s command’s been iffy so far, too.

“He’s a guy that’s got stuff,” Amaro said. “He hasn’t pitched great this year yet. But his stuff has been good. Reports about his stuff and his competitiveness have been good.”

Poor numbers. Bad command. Good stuff. Right.

Pettibone, 22, went 4-1 with a 2.25 ERA after his first Triple-A promotion last year, working his sinker and slider for a 50.8% ground ball rate. 44% is usually average.

“I don’t think he’s going to overpower people,” Manuel said. “He’s gotta have location, command, be able to get his secondary stuff over the plate.”

Pettibone was invited to his first big-league camp this spring, and similarly struggled.

He was knocked around for four runs in two innings against the Braves in his only Grapefruit League outing on Feb. 28, with Chris Johnson and Tyler Pastornicky going yard. And after the Dominican World Baseball Classic roster was done feasting on Cole Hamels on March 5, they snacked on Pettibone for four runs on nine hits in 2 2/3.

Dubee couldn’t tell you.

“He might’ve come in that came,” he said. “I don’t remember.”

Dubee said it’s not his practice to evaluate his arms in spring training, so tomorrow, our first time seeing Pettibone will be his first time watching him.

“He’s coming. I’ll watch him,” he said. “That’s all you can do.”

What about a pep talk? Got one planned?

“Yeah,” Dubee said. “Hi. How are ya? Congratulations. Go get ‘em.”

Perhaps there'd be more pep about one of the organization's two top 100 prospects, lefty Jessie Biddle, 21, (61 on MLB.com, 89 on Baseball America) and righty Ethan Martin, 23, (80 on MLB.com) or even lefty Adam Morgan, 23, who turned heads in camp this year.

But Biddle's not big-league ready, and Martin and Morgan threw yesterday. So it goes.

In fairness, the organization’s not down on Pettibone.

“He’s young and he’s got a chance to be good,” Manuel said. “I saw him, what, two or three innings in two or three outings? Yeah. He’s got good stuff. He’s a pitcher.”

Manuel also managed Pettibone’s dad, Jay, in the minors in the 1980s.

“Sinker, slider,” Manuel recalled. “He was OK. He was pretty good.”

It’s just that no one’s jumping out of their skins about him, either.

Whether they do, and whether they bail on Pettibone after tomorrow, is all wait-and-see.

“Depends on how he pitches, I guess,” Amaro said. “I couldn’t even speculate."