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5/10/2014 7:20 P.M. ET

Bucs yet to determine Grilli's next step

PITTSBURGH -- Jason Grilli threw a 25-pitch bullpen session on Friday, and plans are for him to repeat the exercise on Sunday. He and Pirates staffers agree that he continues to feel good physically and edgy mentally.

What they may not completely agree on is the eventual next step in his comeback from a strained left oblique.

Grilli is not convinced that he will need a Minor League rehab outing "as long as I'm throwing well to guys in sim games here, and using all my pitches."

Manager Clint Hurdle opined, "I think he's going to need some [rehab time]. We'll get his thoughts; he's a part of this."

On April 26, in the wake of two identical blown saves against the Brewers, both on Ryan Braun home runs, Grilli went on the disabled list. Assuming the closer role, Mark Melancon has earned three saves in four opportunities.

Hurdle indicated that the job will be Grilli's when he returns. Before his injury, Grilli had converted four of seven saves.

"I hate to take a guy's job away because of an injury," Hurdle said. "Grilli is feeling fine again. He is starting to feel aggressive."

Hurdle likens Mercer's progression to Ripken's

PITTSBURGH -- Manager Clint Hurdle was referring only to stature, not status, when he recently compared Jordy Mercer with Cal Ripken Jr., so no need to call the sacrilege police. Hurdle recalled the debate over whether the 6-foot-4, 200-pound Ripken was too big for the defensive agility demanded by the shortstop position, and applied the lesson to the 6-foot-3, 205-pound Mercer.

"We all know where the Ripken argument went. If you can play shortstop, you can play shortstop. Jordy has shown to me he can play shortstop," Hurdle concluded.

However, there is another possible basis for comparison not many have touched on: Before dramatically redefining shortstop as an offensive position, Ripken struggled mightily.

In his Major League introduction, in 1981, Ripken went 5-for-39 in 23 games with the Orioles, without an RBI and with an OPS of .278. Carried over to the start of the 1982 season, Ripken hit .125 in his first 39 big league games and drove in four runs.

The only moral here is that Mercer's slow start with the bat this season, his first as the Bucs' starting shortstop, is hardly unique.

Now Mercer is beginning to be able to discuss the rough getaway in the past tense. He posted his first three-hit game of the season on Friday night and entered Saturday night's game vs. the Cardinals with five hits in his last 14 at-bats.

"It was absolutely good to see," Hurdle said of Mercer's contributions to the 6-4 win in the opener of the series against the Cardinals. "It's been tough sledding for Jordy. Hopefully, that kind of a night can settle him down."

"Things are starting to click a little bit for me," said Mercer, who attributes the turnaround to sticking to a consistent approach. "When you struggle, you always want to do 'more, more, more,' and that's not the right way to go about it. Ultimately, with results your confidence goes up."

Wandy scheduled for Thursday return

PITTSBURGH -- Following his Tuesday rehab start, left-hander Wandy Rodriguez had no issues with the inflammation in his right knee that sent him to the disabled list on April 21. Friday's bullpen session had the same postmortem.

So what's next?

Rodriguez is tentatively scheduled for his return start on Thursday in Milwaukee, against the same Brewers team he faced in his last start.

"He's making progress. Feeling better," manager Clint Hurdle said. "So we will announce that he's starting the third game [of the series in Miller Park]."

Rodriguez is not getting a soft landing for his re-entry. He has not matched up well with the Brewers, or with their ballpark, during his career, with a lifetime record of 10-10, including 4-8 with an ERA of 6.39 in Miller Park -- where he has surrendered 15 home runs in 76 innings.

Rodriguez allowed 10 earned runs in 8 2/3 innings in two Miller Park starts last season.

In his April 19 start against the Brewers in PNC Park, he went four innings and yielded four runs.

First number, last word

.524: Neil Walker's on-base percentage for his first nine games of May, reflecting his going 12-for-32 while drawing five walks and getting hit by pitches five times.

"There's seven days in a week. 'Someday' isn't one of them." -- Hurdle, riffing on the Bucs' 2014 mantra, "Now!"

Worth noting

• Jon Hamm and Rinku Singh, the star of and inspiration for the movie "Million Dollar Arm," respectively, will visit PNC Park for Sunday night's game. Singh, one of two Indian pitchers signed by the Pirates through the contest chronicled in the Disney film, will be making what is believed to be his first visit to the park.

• Walker's 14-pitch at-bat against the Giants' Santiago Casilla in the 10th inning of Monday night's game included 10 foul balls -- the most in any at-bat in the Majors thus far this season. (Tip of the cap to Bill Arnold.)

• The Bucs are 8-4 in opening games of series after taking Friday night's game from the Cards. However, they took a record of 4-7 in series' second games into Saturday night's rematch.

Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. This story was not subject to the approval of Major League Baseball or its clubs.