There are two contrasting drafting philosophies that might have a bearing on whether or not we'd draft a RB with our #16:
The late Giants GM, George Young said he believed in "drafting to the strength of the draft" - i.e. if really good offensive tackle prospects were plentiful, you drafted some of those (which is what he did when he drafted Eric (?) Moore with his top pick and Jumbo Elliott with his next pick, helping to propel the Giants to the Super Bowl.
An opposing theory holds that - if there's a ton of talent at a certain position (as often happens at wide receiver - especially in terms of raw vs. polished talent) you can afford to wait until the 3rd or 4th round (because talent will still be available).
I believe that rules are there to be broken and, while you shouldn't totally ignore sound drafting principles, there are times when common sense and judgment come into play specific to a particular draft-slot or player.
For example - If the BPA at #16 happens to be a wide receiver and you don't need one; and there's another player almost as good who plays FS and you're in desperate need of a FS, then you bend the rules a little and draft the FS. But, then again, if you rate that WR miles ahead of anyone else on your draft board at #16, you either draft the WR or consider trading out of the spot (and even then - as we know all to well - moves like that can be fraught with danger).
With concerns to the first part on draft philosophies. I think that each team goes into the drafts pretty much needing to address 5 or more positions that they want to address in the draft. Lets just say for arguments sake this year for the Cards its, RB , CB, OLB, FS, DE and OT (6) in not nesessarily any particular order at this time.
I think the teams that draft well pretty much do address all those particular needs (wants), the real question pertains to which will be the top most addressed areas of want and what falls to you on the draft board.
I think, let say for arguments sake that the Cards feel that out of the positions listed above that they'd like to take a RB, CB and OT on day one (picks 1-3) and in that prefered order. They have a couple RB's rated at 91 say that they think they have a chance at. Then a CB rated at 92 they didn't expect there is still on the board. Then it's up to the org's scouts and brass to ascertain what they believe will be the best talent available to them in the next round, or if they have the possbility to trade to get it. If the draft is deeper in CB's then top RB's then they might go in that direction (take the RB first even though the CB is rated highter).
Now say something really unexpected happens, like a S rated on their board at 94 vs. the RB's at 91. Even though they weren't really targeting a S on the first day, the best one has fallen through the cracks. They liked a few particular players on the second day however. They have to determine whether any of those players will have a impact. If they question that then they probobly need to think outside of the box and draft one of the higher rated players on their board.
That's the thinking that goes into it. It's not just any one or two philosophies but a bunch of factors that determine the drafts outcome. Obviously if you draft high you can target just a few elite players to begin with, but then you need to be more flexable after that initial pick. I think that happened last year when the Cards found Branch still sitting there in the 2nd and became offensive minded to land that unexpected player who they felt would have an impact.
By the way, Dallas has had alot of success trading down the last few years and getting extra picks and targeting pretty good players moving down. They have two 1sts this year after getting Spencer last year moving down. If a high rated player that you don't really need falls to your slot, you have to look at that as your fortune to move down and have a shot at still some good players, if you are flexable enough to target more than one position.