I don't see a huge difference between the Oaklands and the rebuilt Tampas that the locals are excited about in their thread. Both teams have to maximize production from cost-controlled, undervalued assets via platooning, high roster churn and other creative means. One big difference is the Rays were able to lock in their star 3B while Beane had to trade his away but other than that, I think I prefer the A's bats. I don't know if Danny Valencia can avoid regression, Crisp can avoid injury and Semien can avoid errors. You could put bags over the heads of Butler, Alonso, LoMo and Pearce and nobody would complain.
The Rays rotation obviously looks better but a lot can change in a few months. I was surprised Oakland invested so heavily in their bullpen this offseason but I'm always inclined to give their organization the benefit of the doubt in spite of some recent missteps. The West is deeper than it was a few years ago though. I think the A's can be competitive but like the Rays, it's hard to see them getting over the hump.