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4/14/2014 7:01 P.M. ET

Williams calls defensive lapses an 'aberration'

MIAMI -- Since being named manager last November, Matt Williams has emphasized the importance of defensive growth for the Nationals.

Williams even brought in longtime scout Mark Weidemaier as defensive coordinator.

Yet through 12 games, Washington committed 13 errors and ranked last in baseball in fielding percentage (.969). Last season, the Nationals were 24th of 30 teams (.982).

"The way I look at it is, errors have been made, but it's not because we're out of position or for lack of preparation," Williams said. "Everybody gets their grounders every day, everybody works hard every day. You think about it and say, 'Is it an aberration?' I would tend to think that it is."

With injuries to players like third baseman Ryan Zimmerman, center fielder Denard Span and outfielder Nate McLouth, there have been moving parts in the lineup. Williams doesn't see that as a reason for the trouble because guys are playing familiar positions.

In the series sweep to Atlanta, the Nationals made seven errors over three games, including a trio of miscues on consecutive days. Washington recorded at least one error in four straight games before a clean showing in Monday's 9-2 win in Miami.

"It compounds itself certainly when things aren't going your way," Williams said. "Generally, it has a tendency to do that. All that being said, we work hard at it, we prepare for it every day, we do early work, we do extra work. It's not anything you can point that finger to. It's just the way it is and has been.

"What we can do is start again from today and move forward. We've been in good spots and been able to make plays when we needed to. There's been some hiccups, too, but it's not for lack of their work or preparation nor ours. Hopefully, things will get much better, and they will."

Fister completes bullpen session, eyes sim game

MIAMI -- Nationals right-hander Doug Fister took the next step in his rehabilitation process Monday afternoon at Marlins Park.

Fister, who is on the 15-day disabled list with a right lat strain, threw 50 pitches -- including his entire repertoire -- during a two-inning bullpen session.

"I'm definitely antsy, but at the same time I know I need to do this the right way and not rush it," Fister said. "It's another step in the right direction where I want to be in this situation. Feeling pretty good and keep taking steps in the right direction of getting stronger, more in shape and getting back out there."

Manager Matt Williams said the club will continue to proceed with Fister like it would in Spring Training. The 30-year-old pitched just 5 2/3 innings during Grapefruit League play between inflammation in his right elbow and the lat strain.

The next step will be a simulation game to face hitters, but no date has been set. It depends on how he feels on Tuesday following Monday's session. After that, Fister will likely compete in rehab games. Fister believes the timetable for his return remains late April to early May.

"How close is he?" Williams said. "He's as close as feeling good every time he goes out there, and that natural progression will take care of itself."

Frandsen prepared for whatever role Nationals require

MIAMI -- Kevin Frandsen's Nationals biography still labels him as an infielder.

Frandsen, however, started in left field for the third consecutive game Monday night in the series opener against the Marlins.

Entering this season, the 31-year-old had played just 14 career games in the outfield -- one in 2010 and 13 in 2007. Monday marked his fourth outfield appearance in 2014.

"Being a utility guy and being on the field for all four groups during BP for so long, you go out and shag," Frandsen said. "I feel like that preparation there helped me out with certain stuff like that. Obviously, game time is different, and every day's going to be different and a grind. Just making sure you get the right reads and hopefully take the right route and catch the ball."

Less than a month ago, Frandsen found himself without a team when the Phillies released him. The Nationals signed him to a deal on March 26.

Frandsen spent parts of the past two seasons with the Phillies. He hit .338 in 55 games in 2012, but just .234 over 119 games last season. He did lead the Majors with 14 pinch-hits.

Through 11 games in a Washington uniform, Frandsen is 7-for-19 (.368) with two runs and an RBI. He has made the most of his playing time with injuries to various players.

"It's just nice to be on a team," Frandsen said, before going 0-for-4 in Monday's 9-2 win over the Marlins. "It was tough the first couple of weeks. … Obviously excited for my opportunity. Coming in I knew what my role was, and when you get some unfortunate breaks in here with the injuries, it's got to be the next man up.

"I've always said as a utility guy, you prepare to start every day. If you don't, you're behind the eight ball and all that. I prepare myself like I'm an everyday player because that's the only way you do it."

No. 7 prospect Skole delivers clutch hits

First baseman Matt Skole, the Nationals' No. 7 prospect, began the season mired in a deep slump. Entering Monday, he was 3-for-32 this season at Double-A Harrisburg.

After Monday, Skole's slump may be history. He tied the game with a two-out, two-run double in the eighth inning and then hit a walk-off single in the 10th to lead Harrisburg to a 4-3 victory against Altoona.

Skole finished the game 2-for-5 with three RBIs, raising his batting average 41 points to .135. Center fielder Michael Taylor, the club's No. 4 prospect, added three hits and a run.

Skole was the Nationals Minor League Player of the Year in 2012, but missed almost all of last season after he was injured in a collision at first base in the second game. He needed surgery to repair a microfracture in his left wrist and a torn ulnar collateral ligament. He was sidelined for the rest of the season before returning to the field in the Arizona Fall League.

The news wasn't all good for Harrisburg, however. Outfielder Drew Vettleson, acquired during the offseason from the Rays in the Jose Lobaton deal, is expected to go on the disabled list with a broken hand, according to PennLive.com. Vettleson, the club's No. 11 prospect, sustained the injury when he was hit by a pitch Sunday.

Worth noting

• Nationals outfielder McLouth sat out a second straight game with patellar tendinitis in his left knee.

McLouth became a late scratch on Sunday. He was throwing in the outfield when he felt pain.

Williams said no MRI has been done yet, but McLouth's knee is getting better. If Monday marked the final game of the season, he could've played.

"Nate's still sore, really sore today, so they're treating it," Williams said. "They're making sure that when he does get back, that it's good. … It could've pinched something in there to make it sore. Structurally, everything checks out fairly well. There's no cause for concern in that regard. He just tweaked it. It could be sore a couple of days."

• Nationals center fielder Span, currently on the seven-day concussion disabled list, took swings before and during batting practice on Monday. Doctors planned to check on him afterward.

Span sustained the concussion when he collided with Braves second baseman Dan Uggla while running the bases Friday.

"He's going to come back in [Tuesday] and do some more," Williams said. "We may on the last day here send him back to see the doc to make sure prior to us getting home. That's still up in the air."

Christina DeNicola is a contributor to MLB.com. Teddy Cahill is a reporter for MLB.com. Follow him on Twitter at @tedcahill. This story was not subject to the approval of Major League Baseball or its clubs.