CHICAGO -- Right-hander James McDonald has been removed from the Pirates rotation, manager Clint Hurdle said Sunday.

Right-hander Kyle McPherson will take McDonald's spot in the rotation Wednesday against the Brewers.

"You want your starters to pitch well and as the games count down, we've got to look to give ourselves the best shot that we can have at winning a game," Hurdle said. "Based on James' inconsistency the second half, as I shared with him, when James is right, James is a valuable addition to our ballclub. He's had his challenges the second half."

McDonald has a second-half ERA of 5.84 in his past 12 starts, a stark contrast to a first half in which he went 9-3 with a 2.37 ERA. He admitted after Friday's game he had lost confidence.

McDonald is available out of the bullpen beginning Tuesday. Although he has experience as a reliever while with the Dodgers, he hasn't appeared out of the 'pen since coming to Pittsburgh in 2010. Hurdle said he believes pitching as a reliever will be foreign to McDonald, but is confident McDonald will do his best to help in that role.

"It's going to be up to him what he provides and his buy in. That's what we've encouraged him to do," Hurdle said. "There's still a lot at stake for everybody here and he has a role to play on this club. I anticipate him very good with it from that end."

McPherson, 24, has allowed two runs in 11 2/3 innings of relief for the Pirates since debuting Aug. 20. He was 3-6 with a 3.22 ERA in 12 Minor League starts this season between Double-A Altoona and Triple-A Indianapolis and is the club's No. 10 prospect, according to MLB.com.

Hurdle said the club opted to go with McPherson instead of Jeff Karstens because the veteran righty hasn't pitched in a game since leaving Aug. 31 with right hip flexor discomfort. Karstens is 5-4 with a 3.89 ERA in 15 starts this season.

"McPherson has pitched well and there are many people that speak highly of him through our organization," Hurdle said. "We'd really like to see what he can do. He's got a power arm."

With Walker's return, Marte leads off

CHICAGO -- Neil Walker's return to the Pirates' lineup does more than just give Pittsburgh its starting second baseman. It also gives the Pirates a chance to put their ideal leadoff hitter atop the lineup.

Left fielder Starling Marte was back in the leadoff spot Sunday against the Cubs at Wrigley Field. It was the second consecutive day the youngster led off, following Saturday's 2-for-3 performance as the Pirates snapped their seven-game losing streak in Walker's return.

While Walker was out with lower back tightness, Marte batted around the order after returning Sept. 7 from a right oblique strain.

Having Marte atop their order is key for the Pirates. He's hitting .271 with a .311 on-base percentage while leading off, which he's done in 23 of his 27 starts this season. Compare that to the Pirates' leadoff hitters not named Marte, who have a .233 batting average and .281 on-base percentage.

"It's been a challenge in our leadoff spot all year," Pirates manager Clint Hurdle said. "But we know what Starling's capable of. That's why he's going to get reps and that's why we're going to continue to push him out there."

Worth noting

• Sunday is the 37th anniversary of Pittsburgh's largest margin of victory in a game. The Pirates beat the Cubs, 22-0, on Sept. 16, 1975, at Wrigley Field. Rennie Stennett set a Major League record by going 7-for-7 while the Pirates had 23 hits compared to the Cubs' three.

• Second baseman Neil Walker entered Sunday one RBI shy of joining Andrew McCutchen (87), Garrett Jones (77) and Pedro Alvarez (75) in the 70-RBI club. The Pirates haven't had four players drive in at least 70 runs since 2007.