I know Vlad has already written 5000+ words of his Rule 5 Draft preview (yes, really, and if you don't believe me, check out what he did last year), and I'd hate to take any of the fun out of that, but it doesn't sound like the Pirates will pick anyone, or at any rate, they don't sound optimistic they'll be able to carry someone for an entire year.
"Our expectation is, the guys we like will be off the board before we pick. There are some upside guys in the pool, maybe more this year than in the last couple of Rule 5s. This year, there are some guys who have some ceiling, in our (scouts’) minds. Those guys are a bit more challenging to carry (on the roster). We’re in a different state as an organization than we were in 2008 or ‘09, where we worked hard to try to carry a guy. Now, we need somebody who can contribute for us, and that will be a factor. We don’t want to try to compete with a 24-man roster. So even if the ceiling is really high, it could handcuff us."
In addition to the factors Huntington mentions, which are totally valid, there's also the fact that the Pirates will be picking much later in the draft than they typically do. You never know what might happen in the Rule 5 Draft, but as Huntington implies, it's more likely than in previous years that the Pirates won't be able to get the guy they want.
Also, the Pirates haven't carried a Rule 5 pick for any serious length of time since ... well, 2009. Huntington is right that the Pirates are at a point where having an unripe Evan Meek or a Donnie Veal on the roster would be actively problematic. And those were the Pirates' best Rule 5 picks under Huntington. (Pop quiz, and no cheating: Name Huntington's other three Rule 5 picks. The answer is in the comments.)
It's hard to get a handle on who's worth picking in the draft unless you're a scout or you're Vlad, but one guy who might make sense is Josh Fields -- not the infielder and former Pirates Spring Training invitee, but a reliever from the Red Sox organization who has good stuff and took big steps forward with his command this year. My guess is that he'll be gone before the Pirates pick, however.