Most fans don't realize that because of collusion and the new CBA the salary cap remained flat at 123m from 2009 to 2013. That is a long time for 0 growth when the NFL was thriving.
Add the 10m Miles Austin penalty and a few bad deals like Barber, RWill, Ratliff and Hamlin and Dallas was tight against the cap a couple times, but they were never in 'cap hell'.
They were able to sign FAs like Carr, Bern, Livings, Orton and Durant.
They were able to extend Romo, Lee, Church, Scandrick, TSmith, Free and Bailey.
They were able to Franchise tag Spencer twice for big bucks, almost 20m.
And they were never forced to cut anyone solely for cap reasons. DWare was about production vs performance.
Dallas was hampered by poor drafts, poor coaching, poor extensions, poor FO work and still managed to stay competitive at 8-8 while they were being completely rebuilt under JGarrett.