Ever since Christian Parker was hired as the team's new DC, acquiring that "big nickel" was their #1 priority. CP mentioned the importance of this position in his opening press conference. This position wasn't going to be like a traditional nickel corner, but more like a safety who can play the run at a high level, but also hold up in underneath coverage. So happens that Cowboys were fortunate to land Caleb Downs-the ideal fit for what CP wants at this important position.
It's not coincidence that they rebuilt their DL with massive size/strength. They also acquired Gary who is considered one of the best run defending DE's who will now play OLB close to 280.
Add in they hired the former Arizona Defensive Back coach who comes from a system that employed a ton of 3 safety formations. They went long at the safety position have 5 on their active roster, but just 4 linebackers. This suggests we are going to see a ton of defensive backs on the field at the same time.
Biggest defensive question to me is, can they hold up playing the so called "light box" to stop the run? In my opinion, success or failure in this area will determine this year's fate on defense.