Grabow went on the disabled list on March 23 with left elbow irritation. He posted a 0-0 record and a 2.25 ERA in four games with Indianapolis.
"I'm ready to go," Grabow said. "I'm very happy -- everything's back to normal and I'm ready to go. I pitched in a few games in Indy and everything felt good and I'm game ready."
Grabow, who did not pitch in back-to-back games during his rehab stint, will be used judiciously by manager Jim Tracy.
"We didn't want him to," Tracy said. "We talked about it and I discussed the situation with [Pirates pitching coach] Jim Colborn. We really didn't want that because I think we won't get on him and ride him right out of the chute, like we were using him over the course of the last three months of the season last year. We'll build up to that. We'll get to that point, but we won't just jump right in the saddle and ride him."
To make room on the 25-man roster, the Bucs optioned lefty reliever Juan Perez to Indianapolis following Sunday's game in Los Angeles.
Nady update: Pirates right fielder Xavier Nady is considered day-to-day after leaving Saturday's game because of a strained left hamstring.
"My understanding from conversations with [Pirates trainer] Brad Henderson earlier is that [Nady's] leg, the strength of the hamstring, is better than it was on Sunday," said Tracy. "We still have some concerns, but he was in here yesterday and got treated and he felt better. And he feels a little bit better today.
"He's going to take some batting practice to see if he can obviously hit and be effective and not alter things with his swing. And if in fact he's able to do that, he would be available to pinch-hit for us. We would not let him run. He'd hit and we would run for him. But we'll see where he's at. We don't even know if he's available for that just yet."
Tracy indicated a likely timetable barring any setbacks would be a Friday return for Nady, at the earliest.
Castillo to the outfield: Infielder Jose Castillo, who has been the odd man out since the return of Freddy Sanchez from the disabled list, will practice taking fly balls in the outfield with Nady being sidelined.
"We're going to have Castillo take some balls in the outfield beginning [Tuesday]," Tracy said. "He plays the outfield every winter. He plays it all winter long. More times than not he plays more outfield in winter ball than he does the infield. So this is not going to be a new thing for him. But we want to get him some work and let him go out there and run around a little bit. We'll see where it takes us."
Castillo has played both corner outfield spots during his time in the Venezuelan Winter League.
Eldred starts: With right-hander Woody Williams starting Tuesday for Houston, it was assumed that Nate McLouth, who hits left-handed, would get the start in right field in place of Nady. Tracy opted instead for right-handed hitter Brad Eldred.
"We want Eldred," Tracy explained. "I just think from what I've researched and the way things have gone thus far this year, with regard to Williams, it makes more sense to have a power-hitting right-handed hitter in there against him. He's having more trouble getting out right-handed hitters than he is left-handed hitters right now. So we put an extra right-handed power bat in the lineup."
Minor matters: The other player the Pirates received from Atlanta in the Adam LaRoche trade, outfielder Jamie Romak, is off to a sizzling start with Class A Hickory.
In 14 games, Romak is hitting .313 with four home runs, 13 RBIs and a .646 slugging percentage.
Romak outlined his goals for this season, his second in the South Atlantic League.
"Well, I think just getting to the park every day and having a consistent approach and putting together good at bats," Romak stated. "To me, it doesn't really matter where I'm playing if I'm not in the big leagues. I'm still in the Minor Leagues, so there are still things to work on. I'd like to get out of here as soon as possible, but to do that I need to be consistent with everything. And if I do that, we'll win a lot of games and hopefully we'll move up."
The Pirates like what they have seen from Romak so far.
"Everybody likes Romak," said Pirates senior director of player development Brian Graham. "He's raw, but he has raw power and good bat speed. And he's a better outfielder than our reports indicated. I think we have a tools package in Romak."
Indianapolis catcher Ryan Doumit was named the International League's Batter of the Week for the period of April 16-22. Doumit recorded a .423 batting average, .692 slugging percentage, two home runs and 11 RBIs in seven games during the stretch.
"This award is no surprise to me because Ryan is an excellent hitter," Indians manager Trent Jewett said. "He's been a tremendous asset to this team from an offensive standpoint, but I'm most proud of the strides he's made defensively. I've really been impressed with how he's worked behind the plate this year."
On deck: The Pirates host Houston at 7: 05 p.m. ET on Wednesday in Game 2 of the three-game series. Lefty Zach Duke (1-2, 9.00 ERA) will be on the hill for the Pirates. Houston will counter with right-hander Matt Albers (0-0, 3.00 ERA).
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.