Due in part to others being injured, Dukes began this season as Tampa Bay's starting center fielder. The rookie batted .190 with 10 homers and 21 RBIs in 52 games.

He was optioned to the minors on June 22 and placed on the temporary inactive list after he was accused of violating a protective court order his estranged wife obtained after she said the 23-year-old Dukes threatened her and the couple's children.

"We have been committed to providing Elijah the support needed to get his personal and professional life back on track," Rays senior vice president of baseball operations Andrew Friedman said. "He has made progress, and a logical next step is a change of cities and a fresh start for him and his family."

Last week, the Rays traded right fielder Delmon Young to Minnesota in a six-player deal that brought pitcher Matt Garza to Tampa Bay. Young, the No. 1 overall pick in the 2003 amateur draft and runner-up for AL Rookie of the Year this season, famously flipped his bat into the chest of a Triple-A umpire in 2006 and received a 50-game suspension.

Young got a three-game ban in 2005 for bumping an umpire in Double-A. He also argued with Tampa Bay manager Joe Maddon during a late-season game after he was removed for not running out a grounder.

Dukes is the second outfield prospect the Nationals have acquired in the past four days. Last week, they sent catcher Brian Schneider and outfielder Ryan Church to the New York Mets for Lastings Milledge, whose actions had drawn the ire of teammates in New York.