WASHINGTON - The latest reminder of how fragile young pitching is happened last week, when Minnesota demoted its opening-day starter to triple A. For two seasons, Vance Worley mystified hitters as a mainstay in the Phillies' rotation. No one threw a higher percentage of his pitches for called strikes.

The rest of baseball adjusted when the Twins acquired him. Worley allowed 82 hits in 482/3 innings for a 7.21 ERA and became a Rochester Red Wing before May concluded.

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This is particularly relevant to Jonathan Pettibone, the latest unheralded, 22-year-old pitcher to crash the Phillies' rotation. He was not his best Saturday in a 5-3 victory. He still managed his fourth quality start in his seventh career game.

The Phillies, as an organization, are beyond cautious with their younger players. And, oddly enough, they have enjoyed success in the rare instances when an inexperienced starter is pushed into the rotation.

Kyle Kendrick was 22 in 2007 when he started 20 games to a 3.87 ERA. Worley rode a 3.01 ERA to third place in rookie of the year voting as a 23-year-old. Pettibone, 22, has a 3.21 ERA in seven starts. None of the pitchers was ever regarded as a top prospects.

"All three of them probably got here too soon," pitching coach Rich Dubee said.

That makes their success doubly interesting. Pettibone is a boon to this rotation. Every fifth day he cements his standing. Washington smashed nine hits in six innings and stranded six runners on base against Pettibone. He survived. The Phillies are 6-1 when he pitches.

"It's what I'm here for," Pettibone said. "I'm not going to overpower any teams. You're not going to see any complete-game shutouts, at least anytime soon."

Dubee cited those young pitchers' ability to throw strikes as a reason for success. But, he said, a pitcher always has the advantage in an unfamiliar matchup.

"They don't have any track record on you," Dubee said. "They don't know who you are. Plus, as you get up higher, the defense catches the ball better. It's newness. Again, you have to have a full repertoire. Over time, if you don't have one, then the newness wears off."

Even with the abundance of information and video available to the opposition, can that explain a rookie pitcher's success over an entire season?

"As long as you're willing to throw it in the strike zone," Dubee said.

Pettibone became the first Phillies rookie to allow three or fewer earned runs in his first seven starts since Charles Hudson in 1983. There is a lesson there, too. Hudson had a 3.35 ERA in 26 starts as a 24-year-old rookie. He pitched six more seasons, and his ERA was never lower. The names may change, but the game's principles do not.

And while it is a testament to the Phillies' minor-league staff that these young pitchers have excelled when needed, the farm must produce another frontline starting pitcher in the near future. Pettibone's ceiling is probably no higher than a fourth starter, although he will have a chance to dispel that. Kendrick has shaken the notion he cannot be elite, but no one is ready to anoint him a No. 2 starter in the majors.

The Phillies overcame their lack of homegrown talent by acquiring aces Halladay, Cliff Lee, and Roy Oswalt through trades and free agency. Dubee would like to see the opposite occur.

"You draft them and develop them," Dubee said. "That's how you get horses. Look over there."

He nodded toward the Nationals dugout. Washington touted Stephen Strasburg and Jordan Zimmermann, two high draft picks who will spend the majority of their 20s - and perhaps longer - in Nationals uniforms. Ross Detwiler, another top pick, has emerged as a solid mid-rotation man. The fourth and fifth starters, Dubee said, are easily found through free agency.

"Look around the league," he said. "You don't win with all No. 5 starters."

If they found one in Pettibone, it is not the worst development.

Contact Matt Gelb at mgelb@phillynews.com.

Follow on Twitter @magelb.