Marinelli will be working under new defensive coordinator Monte Kiffin, who is shifting Dallas' scheme from a 3-4 to a 4-3. He's been a defensive line coach on many levels, but is most well known for his three years with the Lions, culminating with an 0-16 season. He moved on to be a defensive line coach for the Chicago Bears, eventually becoming defensive coordinator. He was let go after the team missed the playoffs this season and Marc Trestman replaced Lovie Smith as head coach.
The Cowboys have the framework for a talented defensive line - more specifically, they have DeMarcus Ware, and the rest should fall into place - but they'll need some guidance going forward. With Kiffin taking over for Rob Ryan, the team will play a 4-3 after playing the less traditional 3-4 since the 2005 season. That means they'll play four linemen instead of three with a nose tackle. They'll need new personnel - four-time Pro Bowl nose tackle Jay Ratliff is likely gone - and Marinelli will be of use making it all cohesive.