I have now watched 2 drafts unfold. Here, as a beginner, I'm a little surprised at the amount of controversy over this draft. The basics seem pretty obvious to me.
1. As I learned last year, the draft will not pan out according to predictions. This means that in most cases, the greatest-value player will be taken if you take someone who falls. In this case, by the Cowboys' own board, the greatest-value player was Floyd--according to the wisdom of the crowd and the Boys' own board, an exceptional top-10 value, still available at 18.
2. As I also learned last year, it is ridiculous to think that all of your draft picks will immediately contribute at a high level. Players take time to develop. 3rd rounders (and below) do not upgrade a unit, but provide depth/ future starters. And even 1st rounders (e.g., Mo) do not immediately start at elite status. For the Cowboys, this meant 2 things: a) If they took a 1st-round D-lineman, he would not immediately beat out our stellar-when-healthy foursome of Ware, Hatcher, Ratliff, Spencer. b) If they took a 3rd-round-or-below O-lineman, he would not immediately add clarity to our O-line, but merely add to the mix-match of depth.
3. The first round gave the Cowboys two problematic possibilities: a) go with Floyd, and get (according to their board) best value--but knowing he wouldn't start when Ware/Hatcher/Rat/Spencer were healthy; or b) improve their O-line, since the way prospects were flying off their board, they had no assurance that a first-year starter would still be there in the second round. In essence, they were derailed from BPA by a strange draft and by their perception of their needs: a) the strange draft meant that O-line prospects were flying off the board; if they drafted Floyd and waited for their 2nd-round pick, they might not have gotten ANY of the top-2-rounds of O-line talent; b) they perceived that they needed D-line depth, but an immediate O-line upgrade. Thus by taking the best value (by their board) they would give up their immediate upgrade for a guy who will have less sacks then Hatcher-Rat (if Hatcher-Rat stay healthy!).
4. The upside of this move (they aren't just stupid) is that their "loss of value" in trade down was (to switch to Coty's terms) driven by what they valued--what they saw the team needing this year. Their move gave them the best immediate position upgrade, given the strange O-line-heavy-draft; Frederick will indeed make the O-line better. It also gave them another important pick. This year, this was a good choice.
5. The downside is that a draft/ situation which forces you to make such a choice is a draft/ situation that loses you longterm value. Longterm value means not missing on someone YOU think is top-10 on YOUR board. If the top-10 guy who fell to them were an O-lineman (position of immediate need), this would have been "lucky." Since he was a D-lineman (position of developmental need for next year, not immediate need this year), this was "unlucky." That unlucky fact may have also driven an unlucky need to trade down at slightly-less-than-ideal trade value (INSERT DEBATE OVER TRADE VALUE CHARTS HERE).
6. Finally, after the first day, almost the opposite happened. For the rest of the draft, other players who were much higher valued did indeed fall, and the Cowboys took them. (All 3 of their second-day picks were people they had rated in the 20s and 30s.) Those who argue that the Cowboys made a mistake in taking such players (why not bolster a D that has been underperforming, instead of adding more ball-catchers?) miss the point that after round 1, we aren't going to immediately upgrade the team anyway. We're drafting the future--people who have at least a shot at one day replacing Witten or Austen. Meanwhile, the exceptionally deep draft made the "unlucky" nature of the first round (to accomplish our goals we had to trade down for only a 3rd) suddenly look "lucky" (in the 3rd, we found players who are probably going to work out for us better than most years' 3rd-rounders).
7. Did the Cowboys make the right choice? More or less. More--because they had real, good reasons for making real, good moves. Less--because everyone should acknowledge that the 1st round could have panned out in a way that would have been nicer for us, and that made us give up a prospect we thought was really, really good.