Rauch, who took over as the Nats closer when Chad Cordero injured his shoulder in April, was 4-2 with a 2.98 ERA for the Nats this year. The 29-year-old converted 17 of his 22 save opportunities.
"Extremely excited," Rauch said of his reaction when he learned of the trade. "Coming over to a ballclub like this who is winning their division, tied for first I believe right now; a good group of young and old, a lot of stuff to learn, I think, here, and I'm looking forward to getting out there and playing."
Though Rauch closed games for the Nats, the D-backs see him in a setup role for closer Brandon Lyon. With Lyon having pitched three of the last four days, Arizona manager Bob Melvin said that Rauch would close if a save situation developed Tuesday, but going forward he said some combination of Juan Cruz, Tony Pena, Chad Qualls and Rauch would set up Lyon.
"After watching him pitch, and I've seen him quite a bit, he's got great stuff, and his presence on the mound is great, intimidating," Lyon said. "I'm excited to have another arm here and a guy that's been around for a few years. I think it's only going to help."
The D-backs bullpen could certainly use the help. Injuries to Cruz and Doug Slaten as well as some struggles at the normally reliable back end of the bullpen recently, forced Melvin to use starter Micah Owings in a relief role Monday.
"With all that's gone on this season, we're still in a position to win the division and get into the playoffs and have the kind of pitching that can be a factor in the playoffs," Arizona GM Josh Byrnes said. "Jon Rauch has been a very, very good reliever the last few years. Our bullpen has been pretty good this year, it's just been a narrow margin for error; obviously our offense has put some pressure on other parts of the team."
Not only does Rauch help this year, but he is under contract through 2010, and with Lyon and Cruz both free agents following this year, he could help fill the void left by the departure of one or both of them.
|"I know every time you see him coming out of the 'pen for the opposing team, you know you're going to have your hands full."|
|-- Chad Tracy, on Jon Rauch|
Rauch was second in the Majors with 85 appearances in 2006 and led the Majors with 88 last year, and the D-backs put him through a thorough physical exam Tuesday before finalizing the deal.
The D-backs got an up-close look at the 6-foot-11 Rauch three times this year. He tossed a scoreless inning against them at Chase Field in May and one in July at Nationals Park. One day after that, he allowed three runs in an extra-inning win by Arizona.
"I know every time you see him coming out of the 'pen for the opposing team, you know you're going to have your hands full," first baseman Chad Tracy said. "I don't know his numbers for the year, but he's got good stuff, he's got that downhill plane, which makes it tough to hit no matter how hard you throw."
Bonifacio, 23, hit .167 in 12 at-bats for the D-backs this year while playing sparingly at second and in the outfield. Last year, in 23 at-bats, he hit .217.
Signed as a free agent by the D-backs in 2001, Bonifacio has tremendous speed and hit .302 this year for Triple-A Tucson after compiling a .285 average last year with 41 steals in 54 attempts.
"Bonifacio, of course, will be missed," Byrnes said. "[He's] a tremendous person, very well liked in the organization, obviously very fast and a chance to be a very good Major League player. But we felt like we need to make this move."
The D-backs had talked with the Nats about Rauch as far back as last season but were hesitant to part with Bonifacio, a player Washington coveted. One of the reasons the D-backs were reluctant to part with Bonifacio is because he was seen by some as a likely replacement for free-agent-to-be Orlando Hudson.
The club has had talks with Hudson and will continue to do so, but he might wind up being outside the D-backs' price range.
"In many ways, our roster is fairly stable going into next year, and I think that's an obvious issue that, somehow, some way we're going to have to resolve," Byrnes said of the D-backs' second-base spot.
There's been speculation that Arizona could go after A's second baseman Mark Ellis, who will be a free agent in the offseason. And while Byrnes will continue to work the phones, it looks like Rauch and Tony Clark will be the club's two acquisitions before the July 31 Trade Deadline.
"There's sort of wants and then the realistic ability to fulfill those," Byrnes said.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.