By Matt Leon

PHILADELPHIA (CBS) – One of the top pitchers in the Phillies minor-league system is working his way through his first season at Double-A in Reading.

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Righthander Jonathan Pettibone is ranked as the #4 prospect in the Phillies system by Baseball America.   Here in 2012 he has made eleven starts for the R-Phils, going 4-5 with a 3.92 ERA and 42 strikeouts in 66 2/3 innings.  The 21-year-old Pettibone says he has been getting ahead of hitters and that has led to success.

“Commanding that fastball, pitching off my fastball and then, of course, my change-up’s another plus pitch that I’ve been throwing a lot,” Pettibone said. “Slider’s still a little work in progress, but it’s coming along well and I’m pretty comfortable throwing it for strikes.”

Listen to Matt Leon’s interview with Jonathan Pettibone:

Pettibone actually got off to a bit of a rough start in Double-A, but he had been a in a great groove the last several weeks before getting roughed up last time out against Binghamton.  Reading manager Dusty Wathan says that one reason for his early struggles was the overuse of a two-seam fastball that had been introduced to him last season to compliment the four-seamer he already had.

“We made some adjustments, we talked to him about using the four-seam fastball that he can command really well and he went back to that, using the two-seam fastball at times when he needed it,” Wathan said. “He’s not a sinkerball pitcher by any means, but it’s a nice thing to have in your pocket when you need a groundball and you can go to that two-seam fastball.  Once he’s gotten back to that and commanded that four-seam fastball, he’s been outstanding for us.”

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Listen to Matt Leon’s interview with Dusty Wathan:

Pettibone was a 3rd round pick of the Phillies back in 2008 out of Esperanza High School in Anaheim, California.  He has steadily moved up in the system every year – last year for Single-A Clearwater he went 10-11 with a 2.96 ERA.  When it comes to improvement since turning pro, he says he has come a long way dealing with the mental side of the game.

“That’s one thing they stress a lot, the Phillies, especially to the younger guys.  Never really had an idea how to last a full season, how to go about a full season.  It took some time to develop a solid routine.  Each year try and build off that,” he said.

Now Pettibone is spending his season a little more than an hour outside of Philadelphia in Reading and it’s not uncommon at all for players to get called up to the Major Leagues out of Double-A.  So the lifelong dream of the big leagues is both figuratively and logistically very close.  But Pettibone says he doesn’t what to get caught up in “what could be”.

“I would be lying if I said it’s not hard, but at the same time, you’ve got to concentrate on the time being and doing your job here and not letting the big picture get in the way and kind of just staying focused and doing your task at hand.”

Pettibone is scheduled to make his next start on Wednesday night at home against Altoona.

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You can follow Matt on Twitter @mattleonkyw.