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8/10/2013 1:58 A.M. ET

Wandy to throw bullpen session Saturday

DENVER -- Starting pitcher Wandy Rodriguez is set to throw 25 pitches in a bullpen session Saturday, a critical step forward in his extensive rehab schedule.

Rodriguez will work on his fastball and changeup in Saturday's session as he continues to recover from a left forearm injury, Pirates manager Clint Hurdle said Friday.

Thursday, Hurdle said Rodriguez would not be ready to pitch Sept. 1, when teams can expand their rosters to 40 players. However, the bullpen session marks the first time the left-hander will throw off a mound since sustaining the injury June 5.

Rodriguez made 12 starts before the injury, going 6-4 with a 3.59 ERA. Rookie Gerrit Cole has filled in since, holding his own in the Major Leagues with a 3.95 ERA through the first 11 big league starts of his career.

McCutchen exits opener vs. Rockies in sixth

DENVER -- Pirates manager Clint Hurdle nixed any concern that Andrew McCutchen was yanked from Friday night's loss to the Rockies due to his lingering shoulder injury, saying that he simply wanted to give his star outfielder extra rest.

McCutchen exited an eventual 10-1 loss to Colorado at Coors Field in the sixth inning, and left fielder Starling Marte slid over to center field for the remainder of the game.

"We gave him the day off yesterday to kind of work him through some soreness and just got him out then because we felt it was the right move to make," Hurdle said.

McCutchen was scratched before Thursday's 5-4 win over the Marlins due to right shoulder tightness before entering as a pinch-hitter in the seventh. One of the leading candidates for the National League Most Valuable Player Award, McCutchen went 1-for-2 with a first-inning single and a walk before he was pulled. He has been on a tear in August, hitting .571 with six RBIs and four extra-base hits in eight games.

For Hurdle, emotional return to Coors Field

DENVER -- Friday was more than the typical homecoming for Pirates manager Clint Hurdle.

It was not Hurdle's first visit to Coors Field, a place where he spent nearly eight years as the Rockies' manager, in a gold and black uniform. But this time, things were different. This time, he came with a Pirates club that boasted the best record in the Majors.

First among the flood of memories when Hurdle returned to Denver was that of his close friend and former Rockies president Keli McGregor. McGregor, whose initials are inscribed on the right-field wall at Coors Field, died suddenly of a heart attack in April 2010.

Only after the memory of McGregor did Hurdle recall more uplifting moments, like the Rockies' remarkable World Series run in 2007.

"My first thought is Keli McGregor," Hurdle said. "Since I left, the second thought is the flag flying, the 2007 National League Championship flag.

"It was a very, very good place to live. It was a very, very good place to grow, and I was very humbled by the opportunity."

Hurdle, now in his third season with the Pirates, has the most wins of any Rockies manager, finishing 534-625 (.461) before he was fired early in the 2009 season.

But Hurdle said there were no hard feelings about his departure from Colorado. What stays in the forefront of his time with the organization is that the Rockies were the first to offer him his first coaching role as the Minor League hitting instructor in 1994.

"There's nothing but great memories here," Hurdle said. "I was able to spend ... a long time here as a manager. So no, it's all good. This is all about Pittsburgh; this isn't about anything else than us trying to grow as an organization and get good again."

Bucs begin critical stretch away from home

DENVER -- The finish-line is drawing ever nearer, each win putting the Pirates that much closer to finishing over .500 for the first time since 1992.

But with less than two months to play and his team holding onto a lead in the National League Central, manager Clint Hurdle refuses to confront the final stretch with any sense of extra importance.

"Nothing's changed," Hurdle said. "We're going to take it one game at a time; we're going to prepare like we always prepared. This is the part of the schedule that we're in."

Friday, however, does mark the beginning of a critical stretch for the Pirates, who play 12 of their next 15 games away from PNC Park. Though Pittsburgh is one of just three teams in the Majors with 70 wins, 41 of those victories have come at home.

Through Thursday, the club was 41-20 in Pittsburgh and just 29-24 on the road. But Hurdle noted that the Pirates faced similar questions following the All-Star break, when they went 5-5 over a 10-game road trip.

And he knows the Rockies' potent offense has the potential to steal a few games in Denver, especially in the wake of Colorado's crushing 1-9 road trip.

"You're playing a team that can strike quickly," Hurdle said. "They have a very good comfort zone here offensively at home. The numbers scream at ya. We've got to pitch well; we got to catch well; we got to find a way to continue to show up on offense ourselves. So there will be a significant challenge here in Colorado."

Improved plate discipline lifting Bucs' OBP

DENVER -- For a Pirates lineup that ranks in the middle of the National League or lower in most offensive categories, walks have been an essential ingredient to becoming one of the best clubs in baseball.

A keen eye in the batter's box appears to be one of the keys to producing enough runs for victory behind the best starting rotation in the Majors. The Pirates' on-base percentage and walks gradually increased in June and July, and the team is on pace for equally strong numbers in August.

The first steps forward came in June, when the Pirates' OBP climbed from .298 to .312 and drew five more walks (74) than in May. In July, their OBP jumped to .321 with 82 walks, and through seven games in August, that OBP was up to .336. Though the Pirates' OBP this year (.312) puts them eighth in the NL, their average OBP over the last three months would rank fourth.

It is a statistical climb that Hurdle said was due to more than pure coincidence.

"I think it's a conscious effort of just having better discipline at the plate and being calmer, not being in quick strike mode, not trying to jump a fastball," Hurdle said. "Just trying to hit one, trying to have the best at-bat they can for the team. Our numbers are still somewhat pedestrian, but they are improving and ramping up."

Worth noting

• Pirates star Andrew McCutchen had a wrap on his right shoulder before Friday's game but was back in the lineup, hitting third and playing his usual center field. McCutchen did not start Thursday's game because of right shoulder discomfort but did serve as a pinch-hitter.

• The Pirates are just 28-57 in NL West cities since 2008, including 7-9 at Coors Field.

Ian McCue is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.