Jesse Biddle delivered another dominating performance Tuesday night, going a season-high 7 2/3 innings without allowing a run during double-A Reading's win over Altoona.

The 21-year-old improved to 3-3 with a 2.50 ERA, which ranks fourth in the Eastern League. The three guys ahead of him are all at least two years older.

So when will the former first-round pick and Philadelphia native be ready to move up a level to triple-A Lehigh Valley?

"There is a scenario that could happen," said Joe Jordan, the Phillies' director of player development. "But we had a plan in place when the season started. We wanted to start him at double A and see how he did. Obviously he has done well, but he still has things to clean up. The worst thing we could do is get impulsive and put too much stock into six or seven weeks of work."

Jordan said one of the things Biddle needs to improve upon is his fastball command.

"In order to be a good major-league pitcher, you have to command your fastball," Jordan said. "He's done it at times, but that's the one thing that needs to continue to get better. We'll keep an eye on things and if we decide he needs to be challenged by a tougher level, then we'll do it."

Heading into Jonathan Pettibone's start Saturday, he and Tyler Cloyd were a combined 4-0 with a 2.92 ERA in nine starts for the Phillies after opening the season at Lehigh Valley, and the next pitcher who appears primed to contribute at the big-league level is righthander Ethan Martin.

After going 1-2 with a 7.66 ERA in April, Martin has rebounded to go 4-0 with a 2.52 ERA this month.

"I think the biggest problem for him early was that this was his first time in triple A," Jordan said. "He was trying to do too much. He realized he was one level away from the big leagues and he wanted to do great and things got a little fast. He started putting pressure on himself. Once he calmed down with some help from Ray Burris, he realized his stuff can play at every level and he started throwing a bunch of strikes."

Lefty Adam Morgan is expected to start Sunday for Lehigh Valley after being skipped Monday because of minor shoulder soreness. . . . The Phillies claimed Mauricio Robles off waivers from Seattle in the offseason and they've liked what the 24-year-old lefty has done at Reading. He entered the weekend with a 2-1 record, two saves, and a 2.31 ERA. He had struck out 33 batters in 231/3 innings. . . . Brody Colvin returned from the disabled list and pitched in relief Wednesday, but he is expected to rejoin the rotation at Reading soon. . . . Righthander Ryan O'Sullivan, acquired in the Joe Blanton trade last year, is 2-2 with a 1.95 ERA at single-A Clearwater.