The keys to the kingdom in the NFL would come in the form of a GM who could know in advance the injury situations his team would face. It's impossible, of course. Anyone remember a particular season in the Landry years when the Cowboys were hit by a rash of injuries to LBs? I recall it happening, but not when.
NFL teams suffer injuries. It's the nature of the game. But injuries are most destructive when they come to a star player or in a bunch at one position. The Cowboys haven't truly had a rash of injuries in the secondary, but they have had critical injuries to both starting corners. Newman is back, and he is good, but he isn't nearly 100 percent. If Henry and Newman were both healthy, the secondary would look much better. But this is the NFL, and you don't get credit for "if."
In retrospect, the Cowboys would have been better served to take a couple of defensive backs earlier in recent drafts. But in fairness, if they had, and if they had lost, say, Ware and James to injuries, many of us would have complained that a LB-centric defense such as the 3-4 should have been stocked with more depth at LB.
One could argue that the Cowboys should have chosen more wisely than to take Carpenter and Burnett, but the book is still out on those guys. E.J. Henderson looked like a bust for the Vikings until this year, and the light seems to have come on.
A bigger point, though: NFL teams miss on draft choices. All NFL teams miss on draft choices. The best organizations miss on draft choices. On balance, Dallas has drafted pretty well in the post-Campo years. Barber was a fourth round pick, Witten a third. Crayton was a late pick. Reeves was a late pick and has played admirably, given that he is the third option at CB. Jay Ratliff was a great later pick. The jury is out on a few others.
By and large, Dallas has chosen pretty well even if a couple or three high picks are disappointments. If Witten had been a first round pick, you wouldn't complain. If Barber and Crayton had been second round picks, you'd probably feel okay. Same with Ratliff.
In retrospect, it would have been nice to have another corner or two, but it's hard to know in advance exactly where injuries will hit. I think Dallas deserves some criticism for not taking another CB early in the draft, but only mild criticism.