I guess it depends if you want two players with 1st round grades (supposedly #11 and #20 on their board) or two 3rds. But 78 would not have been Jackson or Martin it would have been Trai Turner who they had a 2nd round grade on. The other pick might have been Justin Ellis or Cassius Marsh two players they supposedly liked. If they got Jernigan though Ellis may have been overkill at the 1 tech.
Ok...
26-Lawrence (rated 1st) 47-Jernigan (1st? 2nd?) 78-T. Turner (2nd) 83-C. Marsh (2nd? 3rd?) vs. 16-Z. Martin(1st) 34-Lawrence(1st)...
I don't see the 2 1st's vs 2 3rd's, with the depth of this draft it's hard to imagine you would not be able to get a player rated high. I'm certain there would have been a player rated 2nd at 47 (pretty sure a 1st rounder too), as you said we know there was a 2nd at 78 (T. Turner) and odds are a 2nd at 83 too, at worst a "high" 3rd.
At worst I see 1st, 1st grades vs. 1st, 2nd, 2nd & 3rd
At Best 1st, 1st vs. 1st, 1st, 2nd & 2nd.
Again, I think Z. Martin was the best PICK at 16 and Lawrence a good prospect, but IF you had to have Lawrence (I would never agree with having to have 1 player in a draft), I don't think you can call it "the best move" to pick Zack at 16 and use 47 and 78 to get Lawrence. Not in a draft as deep as this with a team with as many holes as this.