CHICAGO -- Pirates manager Clint Hurdle takes many numbers into consideration when selecting the day's starting catcher.

As fans might have realized by now, Rod Barajas' .196 batting average isn't among the most important -- even if Hurdle went with Michael McKenry in Friday's series opener against the Cubs.

Hurdle was asked prior to Friday's game what he thinks about catcher's ERA, which is the pitcher's ERA when throwing to a particular catcher. Hurdle said he and the Pirates take it into consideration, along with numerous other statistics they deem to best depict how well a battery works together.

Hurdle said the organization pays attention to the length of innings, number of pitches per inning and, of course, doesn't completely disregard how "on" a guy's stuff is that particular day. One of the most important numbers is how efficiently the duo works in tough jams.

"When a runner reaches second base, what's the completion time of the inning, as far as pitches?" Hurdle said. "Different things along those lines you look at. But, no, I'm not a subscriber 100 percent to any of it. I just like to pay attention to it, because everything does tell a little bit of a story."

Hurdle, who sat Clint Barmes for a couple of games earlier this season when the shortstop was struggling, said Friday he has talked about doing the same with Barajas. But, Hurdle acknowledged, many Bucs pitchers enjoy working with the 12-year veteran.

Hurdle understands fans' frustration with Barajas' struggles at the plate, and gets why he is questioned for consistently playing Barajas. But he's going by the numbers -- just not the one fans would like.

"There's no perfect equation for all of it," Hurdle said. "But if you use your eyes and you rely on some numbers and pay attention in a common-sense kind of way, there are other things to read into it besides a catcher's batting average and who should play and when he should play."

Alvarez back in lineup for opener with Cubs

CHICAGO -- Pedro Alvarez returned to the Pirates' lineup for Friday's matinee opener against the Cubs after missing Wednesday's finale with the Reds because of a sore right wrist.

The third baseman said Wednesday the wrist strangely began bothering him earlier that afternoon.

Having Alvarez back was a big boost for the Pirates, who entered Friday on a six-game losing streak but still only three games behind St. Louis for the second National League Wild Card spot. Alvarez has thrived during the day this season, entering the opener hitting .301 in 41 day games.

The Pirates are hopeful three straight day games at Wrigley Field will help Alvarez snap out of his most recent slump, as he came into the series hitless over his last 13 at-bats.

Manager Clint Hurdle said he thinks Alvarez's streakiness is something many young power hitters face, mentioning Hall of Famer Mike Schmidt as one example. Hurdle said the the ability to overcome it is what separates great power hitters from average power hitters.

"If you play every day and you have power-hitting skills, you're going to put up numbers," Hurdle said. "But consistency, that can drive it to another level. And that's what everybody wants, including the hitter, as well as the team or the organization."

Walker pinch-hits, could return to lineup Saturday

CHICAGO -- Neil Walker made his first appearance in over two weeks on Friday, pinch-hitting in the Pirates' 7-4 loss to the Cubs.

Walker, who had missed the previous 15 games with lower back tightness, said he was "close" to returning before Friday's opener at Wrigley Field.

The second baseman struck out with the bases loaded to end the sixth inning.

"He's biting to play and said he could pinch-hit today and he was frustrated he didn't get the result he wanted," manager Clint Hurdle said. "I think we're all optimistic that he could very well be in the lineup tomorrow and be ready to go."

Walker, who has been doing core and leg strengthening to make make sure his back is warm and loose, said Thursday's off-day was beneficial. He took batting practice Friday, which paved the way for his pinch-hit appearance.

"When I started to take batting practice from both sides and hit against [right-hander Jeff] Karstens [Tuesday in a simulated game], the day-after events were the big days for me and I didn't feel great after doing both of those," Walker said. "You just go on how you feel. I'll take batting practice today and see where to go from there."

Worth noting

• Hurdle said Karstens was available in the bullpen this series, and he wouldn't hesitate to use the righty in a variety of situations.

• The Pirates' 91 road home runs this year are third most in franchise history behind 1966 (110) and '58 (93).

• The Bucs have won seven of their last eight series at Wrigley Field.