Considering that the A's ace, and only established starting pitcher (Duke), one of their more promising and most major-league ready young starters (Gio Gonzalez), and their true closer (Joey Devine) are starting the season injured, I am remarkably sanguine about the A's chances right now.
That's because baseball is graded on a curve: It matters less how good you are than how you stack up with the competition. Let's look at the competition in April:
The A's will start the season with an apparent rotation of Braden, Eveland, Gallagher, Anderson, and Cahill. However, the Angels will start the season with an apparent rotation of Saunders, J. Weaver, Moseley, Adenhart, and Loux. Meanwhile, the A's have the better lineup and defense, while each team sports a bullpen best described as "solid but not spectacular" (with Devine's injury I think the Angels have the edge, but it's not a huge one). Come the end of April, I have a hard time seeing how the Angels are going to be in much better shape than Oakland. The A's might be a couple games up or a couple games down, but the Angels team that takes the field in April is running away from no one.
Meanwhile, the Mariners can only start King Felix and Prince Bedard 40% of the time and must put an inferior lineup out there 100% of the time, while the Rangers sport a lineup whose heart of the order has lost Milton Bradley, and retained two aging veterans (Michael Young, Hank Blalock) who used to hit and field a lot better than they do now.
Even the A's "tough April schedule" has been mitigated by the fact that in four games against the Angels, Oakland will not to face A's killer Ervin Santana nor A's and league killer John Lackey, and that in three games the A's will catch a Yankees team that is missing Alex Rodriguez.
In other words, from April 6th at least until Lackey and Santana return, the AL West looks like a group of teams all just hoping to play .500 ball, all pretty much guaranteed to be separated by no more than a handful of games.
Then it's a question of how quickly the A's get Duchscherer back, how soon the young pitchers make the transition from "getting their feet wet" to "approaching their true ability," and so on. By May 15th, Duchscherer could be back or on the way, Cahill and Anderson could be hitting their stride.
If not, I certainly don't like the A's chances, but by May 15th some new injuries could also have hit some of the Angels' core players, so you just try to hang in there the first month, the first week, the first day - you don't have to contend for 162 games all at once. And the A's will contend for the first 6 weeks despite themselves, thanks to circumstance. From there, it's incumbent upon them to get healthier, to start pitching less like "newbies" and more like "oldbies," and maybe even to be pre-emptive and become buyers earlier rather than later.
But if you're looking at the A's starting rotation and saying, "Contend - are you kidding me?" look around at the rest of the AL West. You'll feel better.