Trevor Cahill good pickup for D-backs

The Twitter world had mixed opinions on the Oakland A's-Arizona Diamondbacks deal that sent Trevor Cahill to Arizona and top prospect Jarrod Parker to Oakland, but it seemed most liked Parker's No. 1 potential over Cahill's proven performance.

I like the deal from Arizona's perspective for three reasons:

1. The Diamondbacks needed rotation depth, especially since Joe Saunders and Josh Collmenter are strong candidates to decline from their 2011 performances. They also can shop Saunders, a free agent after 2012, if they desire.

2. I like Cahill better than most, it seems.

3. The Diamondbacks needed a lefty in the bullpen, and Craig Breslow gives them a southpaw who has held lefties to a .227 average in his career.

After a strong 2010, in which he went 18-8 with a 2.97 ERA in his second season, Cahill was every stathead's top candidate to regress in 2011, which he did, posting a 4.16 ERA. In 2010, he allowed a .236 batting average on balls in play, the fifth-lowest average of the past 10 seasons. That figure shot up to .306 in 2011, closer to the American League average of .296 for starting pitchers, and thus the increase in ERA. Critics also would point out that pitching in Oakland has helped, as he has a career ERA of 3.24 at home, 4.71 on the road.

All that is true, but there are positives here as well. He increased his strikeout rate from 5.4 per nine innings in 2010 to 6.4 in 2011. He relies on a sinker and gets more ground balls than fly balls. He has been healthy in his three seasons and doesn't turn 24 until March. He is signed through 2015 at a total cost of $28.7 million, with teams options for 2016 and 2017.

The other thing I like: When he's on, he's very tough. He had 13 starts in 2011 in which he allowed one run or zero runs -- among AL starters, only Jered Weaver, Justin Verlander, James Shields and Josh Beckett had more (Jon Lester and Gio Gonzalez also had 13). If he can gain a little more consistency and learn to avoid the bad outings, he has a chance to remain a solid No. 2 or 3 starter for a long time.

As for Parker, the A's are taking the risk that he'll develop into ... well, something better than Trevor Cahill. After missing 2010 because of Tommy John surgery, Parker returned in 2011 and reached the majors late in the season, even making Arizona's playoff roster. Keith Law ranked him the No. 19 prospect in baseball in his midseason top 50 list, and you can argue he'll be a few spots higher after his command improved in the second half.

Overall, Parker didn't dominate Double-A, striking out 112 batters in 130 innings, and his 112/55 strikeout/walk ratio was merely solid for such a top prospect. Another season removed from TJ surgery will tell more about whether he can harness his stuff and develop into a No. 1. And that's the chance the A's take: Will he?

Just taking the five-year sample from 2005 to 2009, here are the pitchers who ranked in Baseball America's top 10 overall prospects:

Brett Anderson

Homer Bailey

Chad Billingsley

Clay Buchholz

Madison Bumgarner

Joba Chamberlain

Neftali Feliz

Tommy Hanson

Felix Hernandez

Phil Hughes

Scott Kazmir

Clayton Kershaw

Francisco Liriano

Daisuke Matsuzaka

Andrew Miller

Franklin Morales

David Price

Justin Verlander

It's a good list, but with its share of disappointments. And that's the top 10; Parker is more of a top 15 or 20. The point is, he's not a sure thing. But the A's do get a cheap starter for three years, plus some usable parts in Collin Cowgill and Ryan Cook. Looks like it could work out for both sides, but with Arizona looking to repeat its National League West title in 2012, Cahill is a solid acquisition.