Has nothing to do with Elliott, heck I wanted Ramsey as the pick. I like Elliott and I think he can help the Cowboys. I have also been watching and playing this game for over 45 years and as an ex defensive player I know that when the offense can maintain drives it allows the defense to get their wind on the other hand as a defensive players when you have been on the field for a long series then your offense goes out and does a 3 and out forcing you back on the field you really start to suck wind. You see the defenders bent over with their hands on their knees as they are trying to catch their breath. You can play with the numbers all you want but does not change a simple fact when offense can maintain drives and convert 3rd down instead of punting it back to the opposition the defense has more time to rest.
Again, no one denies that. If one defense plays 20 minutes a game and only faces 50 plays a game and another defense plays 35 minutes a game and faces 70 plays a game, yes, that defense is going to get worn down.
The problem is that you are trying to apply that theory to the Cowboys and trying to argue that the reason the 2014 defense was better was they played less than the 2015 defense that didn't have as good a running game. Problem is, the actual stats indicate that despite having as not an effective running game as the 2014 defense, the 2015 defense didn't spend a significant amount of time on the field compared to the 2014 defense. You cited 3rd down conversion rates and again, while the theory makes sense, in reality the 2015 defense was one the field roughly the same amount as the 2014 defense and yet the 2015 had an offense with a much worse 3rd down conversion percentage for their offense.
It's not playing with numbers at all. That's what people say when they can't refute actual data. The numbers are what the numbers are.
And what they seem to indicate is that while Elliott is a great TB prospect, it's unlikely he's going to cause a massive swing in the number of plays the defense faces. That's just reality.