HOUSTON -- Ronny Cedeno was scheduled to begin his rehab assignment with Triple-A Indianapolis on Sunday, and manager Clint Hurdle said it's possible Cedeno and Steve Pearce could return to the Pirates for the weekend series against the Cardinals.

Pearce, who is hitting 5-for-14 since going down to Indianapolis on Thursday, is recovering from a partially torn right calf, while Cedeno suffered a concussion while attempting to break up a double play.

"From what we saw here in three days, [Cedeno] seemed alert, he seemed crisp, [he was] running [with] no problems ... [he had] first-step quickness," Hurdle said. "Get him in some games, and we'll see."

Hurdle said he'd wait for about four rehab starts to determine whether he thinks Cedeno is ready.

"If the at-bats aren't good and he's rusty and it's just not feeling right, we're not going to push him back until he's ready," Hurdle said. "I think Pearce would be another guy along those lines, same type of timetable."

Hurdle said it's difficult to determine a timetable for concussed players.

"Some guys have bounced back in four days, and [Justin] Morneau took a year," Hurdle said. "There was a guy that, if you look at the videotape of that collision, it doesn't look much more significant than Ronny's. But I think that's given everybody a much better perspective for the people who say he hardly even got hit."

McKenry making Hurdle's decisions tougher

HOUSTON -- Michael McKenry's satisfactory play since joining the Pirates in the middle of June could eventually lead to a tough decision for manager Clint Hurdle, once his injured catchers return.

McKenry, who tallied three hits on Saturday, is hitting .333 against the Astros this year. The catcher owns a .263 batting average this season.

"McKenry has done everything you could have asked for a guy to do," Hurdle said, "and we'd like to think that he's proven his worth at this level at this time."

Hurdle said catcher Ryan Doumit could begin his first rehab assignment this week, but he will wait until Doumit makes a few rehab starts before he considers how he will use his catchers going forward.

"I'm not a big hypothetical guy," Hurdle said. "My experience in this game [has taught me that], more often than not, things take care of themselves. So many people stress, worry, spend time making decisions, when they don't need to make decisions."

Hurdle doesn't plan to rein in McDonald

HOUSTON -- James McDonald's 97 2/3 innings pitched are already more than he has thrown in any previous Major League season, but Clint Hurdle said he doesn't plan on being overly cautious with the youngster.

"I don't think we're at the point we need to protect him at 140 or 150 innings, like some organizations will do with younger guys," Hurdle said. "I think what you've got to do is just monitor it and keep an eye on things."

Hurdle said he doesn't want to hinder McDonald's development by limiting his mound opportunities and availability.

"If something flagrant happens, I think we would back away or something like ... a big velocity drop, a big command issue," Hurdle said. "But other than that, how do you build up endurance? How do you build these guys and get these guys to work to the point where they're looking at themselves as workhorses, where they can go pitch 180, 190, 200 innings in a season?"

McDonald didn't appear to wear down substantially as the first half of the season drew to a close. He has allowed three runs or fewer in each of his past 10 starts, though he's failed to get through the sixth inning in three of his past five starts.

Bucs bits

• Kevin Correia's most recent start was his shortest of the season, as he lasted just 3 2/3 innings and allowed five runs to the Cubs. But Clint Hurdle said he doesn't want the starter to overanalyze what went wrong.

"Sometimes [you should] just let it go," Hurdle said. "That's what I do more often than not with these guys. When it becomes continuous and repetitive, then you probably reel them back in and take a little closer look at it."

• Neil Walker extended his hitting streak to 10 games with a 4-for-5 performance on Saturday night. He is hitting .442 with eight RBIs in 11 games against Houston this season.

• Entering Sunday, Pittsburgh had won its past six rubber games in three-game sets.