Charlie Morton will not make his next scheduled start Saturday, manager Clint Hurdle said, due to his recent inconsistency.
Left-hander Jeff Locke, who recently joined the Pirates after the roster expanded, will make his major league debut in Morton's place.
Morton has lost three consecutive starts and did not pitch six full innings in any of them. He has allowed 12 earned runs in 14 innings in those starts.
"For a while there, I was pitching pretty well consistently for a couple months," Morton said. "June and July came around, up and down, up and down. August wasn't very much fun. Lately, when I've been pitching well it's streaky. I'll have two or three good starts and two or three bad starts."
Morton (9-9) was productive in April and May but tailed off in June with an 8.50 ERA that month. He also skipped a start in late June and improved in July before returning to top form in August, when he had a 2.84 ERA in 38 innings.
Part of his early success resulted from a lower arm slot that added motion to his sinker. Morton said he usually felt strong at the end of the season, but the new arm slot has taxed his body in a different fashion.
"I'm not doing a whole new thing with my arm but I'm doing it differently," he said. "It's affected me, there's no doubt about it.
"It's almost like all my pitches I throw are new pitches to me. I'll feel things in parts of my arm where I've never felt a thing before, and then things that used to feel not so great feel fine. It's almost like I'm a totally different pitcher."
Locke, 23, joined the Pirates in 2009 in a trade from the Atlanta Braves, along with Morton and Gorkys Hernandez. He spent the majority of this season in Class AA Altoona, going 7-8 with a 4.03 ERA, before joining Class AAA Indianapolis in August. He made five starts and finished 1-2 with a 2.22 ERA.
"It's a big honor to get a start and obviously something I'll never forget," Locke said.
Members of Locke's family will attend the game. He said Hurdle had not discussed his role beyond Saturday.
"The opportunity's there," he said. "Obviously. [Hurdle said] if I go out there and do well, you'll probably find your way in there again. It's a good feeling."
Ryan Ludwick came off the disabled list Wednesday and was in the lineup, playing right field in place of the injured Jose Tabata. Alex Presley stayed in left field.
Ludwick went on the disabled list because of back spasms Aug. 24, although he said he felt better shortly afterward and quickly started a rehabilitation assignment. He batted .385 in four games at Indianapolis, hit a home run and drove in five runs.
"He went down and worked hard, very good reports on the at-bats and the work put in in the rehab assignment," Hurdle said.
Hurdle said Ludwick made adjustments to his stance and swing before the injury and had started to hit better, then carried those over into the rehab games. In six games before going on the DL, he went 6 for 18 with a home run.
• Before last night, Derrek Lee had hit .500 (8 of 16) since coming off the DL Saturday. He took a seven-game hitting streak into the Wednesday night game and had two homers and seven RBIs in that span.
Bill Brink: email@example.com .