The Pittsburgh Pirates, despite being in their first pennant race in 15 years, have decided to add a rookie to their rotation for the stretch run.

Left-hander Jeff Locke will start Monday against Houston in the opener of a three-game series and six-game homestand. He was recalled from Class AAA Indianapolis on Saturday when the major-league roster limit expanded to 40 from 25.

Locke fills the rotation spot vacated by the release of veteran lefty Erik Bedard last Wednesday.

Locke was 10-5 with a 2.48 ERA in 24 starts with Indianapolis. He also made two relief appearances for the Pirates earlier in the season and pitched 4 1/3 innings.

Locke had a chance to join the rotation and struggled mightily. He was 0-3 with a 6.48 ERA in four starts and pitched a total of just 16 1/3 innings.

However, the 24-year-old Locke believes he is much better equipped to handle being a major-league starter. He had made just five starts at the Class AAA level last year before coming to the major leagues.

"It's been a process to reach this point," Locke said. "Some players develop later than others. Maybe I'm a little bit of a late bloomer, but I really feel I made major strides this year."

Manager Clint Hurdle said he sees a difference in Locke from his brief time in the major leagues earlier in the season.

"I think he's one of the guys who walked out of here with a much better feel and understanding of what the major leagues are about through his experiences last year," Hurdle said. "I think a lot of it was overwhelming at times."