That's way oversimplifying things. It depends on your personnel, and if you can keep teams out of the short yardage situations which open up the whole offensive playbook. We didn't do that very well at all against SF, and really not well against Philly until later in the game. The key with man coverage and why DQ plays it so much is it becomes a numbers advantage and now your safeties are free. They can give support in coverage over the top, they can play close to the LOS to help against the run, provide support to your backers in coverage, free you up to spy a mobile qb, etc. This is what DQ has had so much success with the last few years, and has been a major x factor in confusing offenses. A team like SF though plays a heavy percentage of plays in zone, but they also have four guys along the LOS who can both stop the run and rush the passer so they don't care about the numbers game as much. The Cowboys have one obvious flaw in doing that....and that's the fact that most of their guys along the front seven are one dimensional players. That doesn't mean they are bad players by any stretch, but Hankins gives you nothing in the pass game. Parsons can be a liability against the run, Evans is a pure run plugger at LB, LVE if he comes back is a stronger coverage backer than run defender, and you can go down the list but those are the most obvious examples. The Cowboys style works great if they can force negative plays and keep offenses predictable so they can get the right players on the field at the right times. If they just sit back in cover 2/3/4 looks all game they need their best pass rushers on the field as frequently as possible which has the makings of a Arizona game all over again. This is one reason why they reached for Mazi Smith IMO. If he can develop into a true dual threat player on the interior it gives the Cowboys even more flexibility on the style of defense they can run....that's starting to get a little off topic though.