Phoenix, AZ (Best E Casino) - The Arizona Diamondbacks acquired reliever Jon Rauch from the Washington Nationals on Tuesday in exchange for infielder Emilio Bonifacio.

Rauch, 29, is 4-2 with a 2.98 earned run average and 17 saves, having taken over the Nationals closer's role from the oft-injured Chad Cordero earlier this season. In 48 games, the righty has walked seven and struck out 44.

"Rauch is a proven late-game reliever who we control through 2010," Arizona executive vice president and general manager Josh Byrnes said. "We are pleased to add him as we attempt to defend our division title."

At 6-foot-11, Rauch -- the tallest current major-leaguer -- led the majors with 88 appearances last season and was 8-4 with a 3.61 ERA and four saves. He appeared in 85 games in 2006 with a 3.35 ERA.

It remains unclear whether Rauch will step into the closer's role in Arizona. Chad Qualls closed out the D'Backs 2-0 win over Chicago Monday night in place of the struggling Brandon Lyon. Lyon blew his fifth save of the season Saturday, allowing five earned runs on five hits in just two-thirds of an inning as Arizona dropped a 6-5 decision to division-rival Los Angeles. This comes a day after Lyon held on for the save in a 3-2 win over the Dodgers. Lyon barely held a 3-0 lead in the ninth, giving up two runs on three hits in the ninth.

Bonifacio, 23, has appeared in eight games this season for the Diamondbacks, batting .167 (2-for-12) with three runs scored, a double and two runs batted in. He was named to the Pacific Coast League All-Star team with Triple-A Tuscon this season and was named to the World Team in the Major League Baseball Futures Game.