My problem with your logic basically boils down to this:
(1) I think you're too pessimistic about re-signing Crabtree.
(2) I think the WR you draft at #31 or #34 will have less impact on our team THIS YEAR than a DB or DL.
As for (1), I think we can afford Crabtree at Vincent Jackson or Dwayne Bowe money, and I don't think he's crazy enough to think he deserves Megatron money. His negotiation may not go quite as smoothly as we'd like, but I'd be shocked if he leaves. (Great article from AB83Rules: http://www.ninersnation.com/2013/4/7/4192766/49ers-salary-cap-michael-crabtree-future-contract-comparisons)
Regarding (2), the 49ers are the current Super Bowl favorites of the NFL. So while a good GM is always undoubtedly "planning for the future," in this case Baalke needs to plan for the present as well. It's the same reason I raise my eyebrow at all the insistence of trading #34 for a 2014 pick. Sure, that would be fun when next April rolls around, but how does that help us hoist the Lombardi in February?? A good GM can be prudent about the future while also loading up for the present. For the 49ers, that means taking the highest-impact players possible early in the draft. We have an amazing five picks in the first three rounds, which are the rounds where you expect impact starters.
At WR, we already have one of the best one-two punches in the NFL with Crabtree and Boldin. And, fingers crossed he's a breakout player rather than a bust, we have Jenkins who was JUST drafted at the slot you're now advocating burning ANOTHER pick. I haven't even mentioned Manningham or Williams yet (both highly capable #3 types), or the fact that we have another pass catcher on the roster named Vernon Davis.
When you advocate not addressing the S position until later in the draft, I think you're severely diminishing our chances of fielding an elite secondary in 2013. Similarly, when you advocate not addressing the DL until later, I think you're severely diminishing our chances of maintaining an elite front 7 through inevitable fatigue and injuries in 2013.
Our offense is in great hands. Elite OL coming back, CK's star ascending, and all the skill players coming back and improving. It's currently our defense that risks taking a step backward.
EDIT: Caveat to my "all the skill players coming back" comment: I advocate replacing Delanie Walker within the first 3 rounds as well. Love Travis Kelce.
[ Edited by LieutKaffee on Apr 13, 2013 at 1:51 PM ]