WASHINGTON -- Nationals right-hander Todd Coffey was placed on the 15-day disabled list, retroactive to April 9, with a left calf strain, according to general manager Mike Rizzo.

Coffey, who is expected to return April 24, was 1-0 with a 6.32 ERA in five appearances this season. He was signed as free agent in the offseason and last pitched on April 8.

"It felt it like a cramp," Coffey said. "The doc looked at it a couple of times, everything checked out. It's just a small strain. It's a day-to-day type of thing. I'll be ready to go by [next] Sunday. No player ever wants to go on the DL, but it makes more sense this early in the season. You don't want to go out there and have something that is nagging. I'll take the seven days and let it heal."

With Coffey sidelined, right-hander Collin Balester was recalled from Triple-A Syracuse after working five scoreless innings of relief this season. Balester, 24, made 17 appearances for the Nationals in 2010, finishing with a 2.57 ERA and 12 strikeouts per 9 innings. Overall, he is 4-12 with 5.29 ERA in 39 career games, spanning three seasons at the Major League level.

Riggleman has been impressed by rotation

WASHINGTON -- Nationals manager Jim Riggleman is happy the way the starting rotation has performed in the early part of the season, and he is confident his starters will play a vital role in the club's success moving forward.

The Nationals and Colorado are the only two teams in Major League Baseball that have had their starters go at least five innings in each game. Riggleman said Saturday's rainout against the Brewers did not affect the rotation, despite the fact that the club had to play a doubleheader Sunday.

"That's where it all begins, literally," Riggleman said of the starting staff. "Starting pitching is where you put it together to begin with. How far that starter goes has so much impact on the rest of the game, the rest of the month. It really allows you to use your bullpen the way you want to use it. Starting pitching is crucial. Our starters have really done a good job."

Jason Marquis (0-0, 3.65 ERA) got the start for the Nationals in the first game against Milwaukee's Yovani Gallardo on Sunday. Marquis battled an elbow injury last season, but Riggleman is confident the right-hander is fully-healed.

"He's feeling better," Riggleman said. "He had some things he was pitching through early in the year last year, and then just got to the point where he said, 'I gotta get this checked out,' and he did. They removed some loose bodies in there in the elbow and he pitched pretty good after that. But he's really been good throughout the spring, and he's had a couple good starts for us. We just hope that continues."

According to Riggleman, if Marquis and the rest of the rotation stay healthy, expectations will remain high for the club this season.

Nats have three of top 34 Draft picks

WASHINGTON -- The Nationals have three of the top 34 picks in the 2011 First-Year Player Draft, including the sixth overall selection. Washington will also gets the 23rd and 34th overall picks as compensation for Adam Dunn signing with the White Sox as a free agent.

Washington has not picked sixth overall since selecting Ross Detwiler in 2007. Some of the notable players taken in the past with the sixth overall pick were Derek Jeter (Yankees, 1992), Barry Bonds (Pirates, 1985) and Gary Sheffield (Brewers, 1986).