Hiring good people is hard, though in some cases it might not matter as much as others. If I am hiring entry level developers or DBAs, I have a lot of candidates, I'm not investing a lot, and I shouldn't be too concerned if I have to let someone go and find a new employee. Given the fact that the people are often unproven in this case by definition (they're junior levels), I should be prepared as a manager to make more mistakes at this level.
However at the senior level, hiring needs to be done more carefully. The high costs, the limited number of candidates, the responsibilities I give senior people, along with the trust I need to bestow upon them means that I can't afford to make the same percentage of mistakes at the senior level. Most importantly, I don't want to hire expert beginners instead of experts at this level.
I ran across a post on a way to hire senior developers that I thought was very interesting. In particular, I was struck by the analogy of hiring a guitar player. For the most part, I'd agree that if I wanted an experienced guitar player, I'd want the expert, not the expert beginner. If for no other reason than I don't want to argue with an employee that does things my way, including making the same mistakes I'd make, and then explaining to me this is how I had specified things to be. I want a senior people to warn me, and influence me to do better.
I'm not sure how I'd devise a similar level of test for a senior level DBA, though I do like the idea of giving them some scenario or simulation that has flaws or problems and seeing if they'd correct them, point them out, or leave them in place as they moved on to "play" the scenario. I'm sure there's a way to do this, and a balance between how to evaluate the responses.
Ultimately I want senior people to fix things, make them better, and provide a smooth path to increase quality. I want them to point out flaws, and warn me about issues. If I insist on making poor choices, I want their support, but if they can influence me to do better, I'd prefer they did. That's one mark of a senior person.