In another move, the D-backs dealt closer Jose Valverde to the Astros for pitcher Chad Qualls, infielder/outfielder Chris Burke and pitcher Juan Gutierrez.
Haren, 27, has won at least 14 games in each of the past three seasons for Oakland. Last year, he was 15-9 with a 3.07 ERA, he was 14-13 in 2006 and 14-12 in 2005.
Not only has Haren been effective on the mound, he's cost-effective off it. The right-hander is under contract for $4 million in 2008, $5.5 million in 2009 and there is a club option for 2010 for $6.75 million.
With the market for starting pitchers extremely tight, Haren's name was mentioned often in rumors that swirled around the Winter Meetings last week in Nashville, Tenn.
"Definitely relief," Haren said when asked how he felt after hearing he'd been dealt. "I'm all over the Internet and newspapers, even though I shouldn't be, and I saw my name out there so much. They [the D-backs] were definitely one of the teams that if I did get traded I was hoping I would go to. Like I said, the organization is headed in the right direction."
While there were many suitors for Haren, the D-backs matched up well with the A's because of the amount of well-regarded prospects they had in their system. Parting with
pitchers Brett Anderson, Greg Smith and Dana Eveland, along with outfielders Carlos Gonzalez and Aaron Cunningham and first baseman Chris Carter, though, was not an easy decision to make.
Arizona officials wrestled over the past week with just how much they were willing to give up for Haren.
"We presented a rare circumstance for them where they [the A's] could get so many good players," Byrnes said. "They understood our desire not to really strip apart our 2008 team, so our interests were fairly aligned. It just took a while to make the trade work because of the magnitude of it, very good prospects going one way and one of the best pitchers in the game coming our way."
Robertson appeared in three games for the A's last year, but had a good year at Triple-A Sacramento, where he was 4-1 with a 4.35 ERA in 31 relief appearances.
The D-backs like Robertson's breaking ball and like his Minor League track record.
Arizona now heads into Spring Training with a rotation of Brandon Webb, Haren, Randy Johnson, Doug Davis and likely Micah Owings in the fifth spot. Webb, Davis and Haren all have a history of throwing 200-plus innings a season, while Johnson when healthy has done likewise.
By trading so many prospects for Haren, the D-backs are clearly banking that he's the guy to help them advance even farther than they did last year when they were swept by the Rockies in the National League Championship Series.
"I don't like to walk guys," Haren said in describing his style on the mound. "I usually try to make the guys swing the bat to get on base. I would probably describe myself as aggressive, and then when a situation comes where I need an out, I will always go to my split-finger. My split-finger is obviously my best pitch. I throw that and a curveball for strikes.
"I pride myself a lot in durability, and the last three years I've gone over 200 innings and it's something I plan on doing for the next couple of years, too. I do a lot of working out in the offseason and I really take a lot of pride in what I do."
It's been a hectic week for Haren. He and his wife, Jessica, welcomed son, Rhett, into the world on Tuesday.
"I've probably slept four hours since she went into labor," he said.
As he heard the rumors about possibly being traded to Arizona, Haren asked around and got good reports on the D-backs organization. Former teammate Barry Zito told Haren he thought he would enjoy it there.
"I'm extremely excited," he said. "Just having spent a couple of Spring Trainings in Phoenix, me and my wife really loved the town. There's just so much to do. The team is obviously on the rise, a lot of young guys, looks like a fun team to be on, looks like a loose clubhouse, which is something I really liked in Oakland."
Gonzalez was regarded as the club's best position player prospect, but he became expendable when Arizona signed Eric Byrnes to a three-year, $30 million deal last August. The D-backs appear to be set in the outfield for the next several years with Byrnes, Chris Young and Justin Upton. The club also could have felt free to deal Gonzalez because of the presence of outfielder Gerardo Parra, who played at Class A Visalia and South Bend last year.
Smith and Anderson were both highly regarded pitching prospects in the organization. Smith, a sixth-round pick in the 2005 First-Year Player Draft, had some injury issues last season, but pitched well in the Arizona Fall League and could have had a chance to pitch for the D-backs at some time during 2008.
Anderson was selected out of high school in the second round of the 2006 First-Year Player Draft and was arguably the organization's best pitching prospect other than Max Scherzer. Anderson, who will turn 20 in February, started last year with South Bend before being promoted to Visalia.
Cunningham, 21, was acquired last summer from the White Sox, and in 31 games for Double-A Mobile, he hit .288 with five homers and 20 RBIs while compiling an .898 OPS.
Eveland, 24, was acquired by the D-backs from the Brewers prior to last season. Scouts rave about the left-hander's stuff and he's always put up good numbers in the Minor Leagues, but he has yet to translate that success to the big league level.
Carter, who will be 21 next week, was picked up during the Winter Meetings from the White Sox in exchange for outfielder Carlos Quentin. Carter hit .291 with 25 homers and 93 RBIs for Class A Kannopolis.