PHOENIX -- The D-backs are in a win-now mode and they showed it Friday, dealing one of their top pitching prospects to the A's in exchange for right-hander Trevor Cahill and left-hander Craig Breslow.

The D-backs also received an undisclosed amount of cash in the deal, which sent right-handers Jarrod Parker and Ryan Cook and outfielder Collin Cowgill to Oakland.

In one fell swoop, the D-backs accomplished two things off their to-do list -- adding an experienced starter to the rotation while getting a second left-hander for their bullpen.

After surprising most observers by winning 94 games and the National League West last season, the D-backs decided they needed another veteran starter for the rotation to compete for another title, and they were willing to discuss Parker, something they have been loath to do in the past.

"If we didn't feel like we had the depth in starting pitching it would have been a tough deal to make," D-backs GM Kevin Towers said. "But we see a window here specifically in the NL West. Winning a division, we're in a go-for-it mode to kind of stay on top of the division and do whatever that we can. I think it shows the ownership's support to go out and make a deal like this. We still feel have a lot of starting pitching depth as well coming along."

That young pitching includes other top prospects on the brink of making the big leagues in Tyler Skaggs and Trevor Bauer in addition to other pitchers like Patrick Corbin, Wade Miley, Charles Brewer and David Holmberg. As such, the D-backs could afford to part with Parker, who was rated their No. 2 prospect in MLB.com's most recent rankings.

Cahill appealed to the D-backs for a number of reasons. First, he has more of a big league track record than Parker, who was the team's first pick in the 2007 First-Year Player Draft. And Cahill's record is very good.

"He's a sinker-ball pitcher, which we think plays well at Chase Field," Towers said. "[A] proven winner, innings eater, a young guy that we think only is going to get better. Heavy sinker with a plus-plus changeup and a guy that competes and somebody that we think after winning the division makes our ballclub that much better."

Last season, Cahill was 12-14 with a 4.16 ERA while tying for the American League lead with 34 starts. He was better the year before, when he went 18-8 with a 2.97 ERA in 30 starts.

The difference between 2010 and 2011, Cahill said, was a falloff in command something he thinks can be corrected.

"Kind of surprised," he said of the news he'd been traded. "I heard a lot of other guys' names bounce around, and until the last couple of days, I never thought I'd be at least the first one to go. I think it's going to be good. I really liked Oakland and was comfortable over there, but it looks like the Diamondbacks want to win and I really want to compete and try to win a championship so I think it's good."

While he has experience, Cahill is still young -- he will turn 24 on March 1, so he's not much older than Parker -- and even more attractive to the D-backs is the fact that Cahill is under contract potentially through 2017 at a relatively reasonable cost.

Last April, Cahill signed a five-year deal worth a guaranteed $30.5 million with a pair of club options. He will make $3.5 million in 2012 and then $5.5 million, $7.5 million and $12 million. The club option for 2016 is at $13 million, with a $300,000 buyout, and the 2017 option is for $13.5 million, with a $500,000 buyout.

Cahill joins a rotation that is likely to include Ian Kennedy, Daniel Hudson and Josh Collmenter. Towers said that the acquisition of Cahill does not mean that the club will not bring back veteran Joe Saunders, but he added that the two sides are far apart on negotiations on a two-year deal. If they can't reach an agreement with Saunders, they will either trade him or non-tender him at Monday's deadline rather than offer him arbitration.

Breslow, meanwhile, gives Arizona another lefty in the 'pen to go along with Joe Paterson. While Paterson is mainly a left-handed specialist, Breslow's career splits are just about even. Right-handers have hit .224 against the 31-year-old over parts of six seasons while lefties hit .227.

"I don't think I'm terribly quirky or I don't throw from a low arm angle or have a big sweeping breaking ball, but in my career I've been pretty successful at getting both lefties and right-handed hitters out," Breslow said. "Hopefully, I'm a guy that will be counted on to face more than one hitter and I can a throw an inning or multiple innings at a time."

Skaggs and Bauer could compete for the No. 5 spot in the rotation along with the club's other young pitchers, or the D-backs could still add another starter especially if Saunders departs.

"With Trevor in the fold right now our rotation is that much better," Towers said. "It's not to say that we're done doing business. We'd like to add even another starter. With Jarrod out of the picture now, he was kind of penciled in as our fifth starter, so I would have to say at this point, we're still looking to improve the rotation if we can."