You say that the first four picks should be used on DE, OLB, WR and OG; and you seem OK with a corner as our fifth pick. My guess is that this might be your order of priority of these needs.
Does it make sense to you to draft in order of need?
Maybe, IN THIS DRAFT, there are many 4th round WR's who have similar projected value to us as those available in the mid-second. Is this possible or reasonable?
Perhaps, there are no guards in the first couple of rounds that are available anywhere near where we value them. How many of those note named Pouncey would you give a 53 for? Would you really give a 22 for Pouncy (I think that he's a likely first rounder)?
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Others may have different priorities for the early rounds than you do, perhaps including TE or RB.
However, given your stated priorites, I could see us drafting as follows:
DE first or second round
OLB first or second round
WR fourth round (or third with a trade down)
OG perhaps a 4th or later, perhaps nothing at all
RB 2nd round
CB 2nd round
TE another free agency signing and a 6th
Safety is the deepest spot on the defense. I can see a fourth or fifth round pick invested on a CB, though, to compete with Wilhite and/or Wheatley. I sincerely hope that we don't invest a second round pick on one though. Our first four picks should be used on a DE, OLB(s), WR, and G IMO.