Earl Thomas over Mays was a no-brainer. In most 3-4 schemes, all 4 of your DB's in a standard package need to be quick pass defenders as opposed to run supporters. We happened to luck out with Polomalu in that he's adept at just about any role he's asked to fill. I think Mays will end up being a LB at some point anyway unless he sheds some weight. As for Thomas, he's a true centerfielder and ballhawk, which is what we need badly, so things like Chris Chambers (Chiefs game) being left alone to catch a game-cinching bomb don't happen anymore. I think he's alot closer to Eric Berry in the overall Safety rankings than he is to Mays.
In the interest of full disclosure though, I heart Bryan Bulaga and that's the guy I desperately wanted with this pick. The next 2 rounds will probably be O-linemen, unless some obvious talent really drops.