https://www.dallascowboys.com/news/brooks-expect-cowboys-to-use-some-3-4-looks
Nice article from Brooks, explaining a few different defensive alignments and the players that for those roles.
It will be interesting. I think Jaylon Smith could be one of the key players in the ability to shift schemes because of his versatility as a pass rusher.
Let's say we start off with a 4-3 look with Aldon Smith, Poe, McCoy and Lawrence on the line and Lee, LVE and Jaylon Smith at linebacker. We could shift into a 3-4 by dropping Aldon Smith or Lawrence to linebacker and lining Jaylon Smith up as the other OLB. The main question for me would be whether Smith and Lawrence can drop into short-area coverage. If they can, then it will make it more difficult for the offensive line to read the pressure.
We could 1) rush Aldon Smith or Lawrence for a traditional pass rush; 2) rush Jaylon Smith instead; 3) rush Aldon Smith/Lawrence and Jaylon Smith as a blitzer; or 4) rush someone else like LVE as a blitzer with either Aldon Smith/Lawrence dropping into coverage or Jaylon doing it ... unless we wanted to rush six.
I am hoping that we have the personnel to go 5-2 some with Aldon Smith, Crawford, Poe, McCoy and Lawrence being the primary candidates right now for that front since they give us a mix of players who can put some pressure on the passer but also play the run well. We could even have Smith or Lawrence bail to drop into a 4-3, if they can handle that role. (Smith has shown that he can, but he's put on quite a bit of size since then.)