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4/20/2014 6:02 P.M. ET

Storen picking up where he left off last season

WASHINGTON -- When Drew Storen returned from a midseason demotion to Triple-A last year, he was a much different pitcher. And in 2014, that change has held.

The Nationals right-hander entered Sunday with eight relief appearances. He'd thrown seven innings, holding the opposition to one run on two hits, with no walks, nine strikeouts and an .091 batting average.

When Storen was sent down late last July, he had a 5.95 ERA and .295 opponents' average in 42 1/3 innings. In 26 1/3 innings since, he has a 1.37 ERA and a .174 average, with six walks and 24 strikeouts.

"That was big for me to end last year on a good note and get back to pitching like myself and attacking guys," Storen said. "And I've tried to build off that at the start of this year."

Upon returning in mid-August, Storen had gone back to using a more athletic leg kick in his delivery, and he's also changed his pitch mix. In the first part of 2013, before his demotion, he threw about 25 percent four-seam fastballs and 31 percent two-seam fastballs to go with his changeup and slider, according to BrooksBaseball.net. Since then, he's used about 46 percent four-seamers and 18 percent two-seamers.

Storen downplayed that change, but said his usage depends both on the hitter and the situation. For example, lefties see more two-seamers and changeups than righties, while four-seamers are more conducive to getting swings and misses than ground balls.

"It's about mixing it up, because a lot of times those guys are trying to guess where it's going to go," Storen said. "It makes a significant difference when you mix them up."

Storen had one of his best and most important showings Friday against the Cardinals, when he entered with runners on second and third and one out in the eighth inning, protecting a 3-1 lead. He got Matt Holliday to foul out and Allen Craig to ground out while using only five pitches, and the Nats hung on for the win.

It's early, but if Storen is back to being the pitcher who posted a 2.64 ERA from 2011-12, it would be a huge boost for Washington's bullpen.

"Any time you deal with adversity, it's tough to get through that stuff, but once you get on top of that, it makes you better," he said. "It's a tough game. But that's part of it."

Harper in lineup day after being pulled out of game

WASHINGTON -- Just as Nationals manager Matt Williams said after Saturday's game, left fielder Bryce Harper was right back in the team's lineup for Sunday's game against the Cardinals. Harper was batting second a day after getting pulled to start the seventh inning for not hustling to first base on a ground ball back to the mound.

Harper's teammates continued to say they weren't surprised at what happened. Relief pitcher Drew Storen pointed out that the team had meetings on the subject before and during the season and agreed to the rules Williams enforced.

"I respect it, because you know what, you can't bend the rules," Storen said. "It is what it is. It's part of it, part of the game."

Kevin Frandsen, who replaced Harper in left field Saturday, described it as an unwritten rule.

"That stupid unwritten rule thing, it's not stupid, it's just how the game is supposed to be played," said Frandsen, whom the Nationals signed near the end of Spring Training. "So it didn't surprise me."

Frandsen remembers seeing the same type of situation occur while playing for the Phillies the past two years. In that case, it was veteran shortstop Jimmy Rollins who got in trouble with then-manager Charlie Manuel over a lack of hustle.

For example, Rollins was benched during a game against the Mets in August 2012 for jogging to first base after hitting a popup that was dropped. That prevented Rollins from having a chance to take second on the play.

"I just got to a place where it's a reflection on myself," Manuel said at the time. "It's a reflection on our team. It reflects on our organization."

Harper, on the other hand, is only 21. While there have been situations in which he might have shown a lack of hustle, there have been others in which he might have gone too hard on the bases or in the field, even resulting in injury.

It's a delicate balance for such a young player to find.

"It's part of the learning process," Storen said. "You hear it all the time about how young he is and for him to be learning and developing at the big league level, it's pretty tough to do. And he's got all the expectations and all the spotlight on him, so he's got a lot. He's done a great job."

There were no issues with Harper's hustle Sunday. He went 1-for-4 with a walk, running hard on both of his two groundouts in Washington's 3-2 win. He also picked up his first stolen base of the season in the eighth.

Williams said he had a good talk with Harper before the game.

"[I] just sat with him for a couple minutes at his locker and told him I'm confident in him and proud of him and he was going to have an impact today, which he did," Williams said. "He had an impact getting a hit, stealing a base and giving us another opportunity. [He] made some nice plays in the outfield. [He] did well."

Hairston progressing, but sets no timetable on return

WASHINGTON -- Nationals outfielder Scott Hairston, who is on the disabled list with a left oblique strain, has been taking swings in the batting cage and hopes to progress to a Minor League rehab assignment soon.

Hairston was set to hit in the cage for the third time before Sunday's game, taking cuts at about 75 percent intensity. If that went well, he would progress to hitting on the field, shagging fly balls and going through other normal pregame activities with the team. A rehab assignment would follow after that. With all of those steps to make, Hairston was hesitant to set a target date for his return.

"I'm just setting really small goals right now," said Hairston, who was placed on the 15-day DL on April 6. "We'll complete steps one and two before we see the finish line."

Hairston did say he considers himself to be "right on schedule," since he hasn't suffered any setbacks. But having dealt with oblique issues in the past, he also knows that progress can prove fleeting.

"It's one of those things where it can feel all right. Then you go out there and take a game-like hack and you're back to square one," Hairston said. "So you really have to make sure you're healed and ready to go."

Worth noting

• Center fielder Denard Span, who returned from a concussion to pick up two hits Saturday, was in the lineup Sunday.

• Third baseman Anthony Rendon hit fifth for a second consecutive day after never before filling that spot in the lineup.

Andrew Simon is a reporter for MLB.com. Follow him on Twitter @AndrewSimonMLB. This story was not subject to the approval of Major League Baseball or its clubs.