The Cowboys move to the 4-3 defense is music to Leon Letts ears. Hes going to get a chance to teach what he knows.In a 3-4 you did more of a read-and-react. This is more of a react-on-the-run rush the quarterback and then react to the run on the way to the quarterback, he said last week as the Cowboys assistant coaches met with reporters. Kind of the same thing I did as a football player, so Im kind of used to it, and Im looking forward to teaching it and coaching it."Lett collected 22.5 sacks and 229 tackles in a 10-year career with the Cowboys, twice making the Pro Bowl. He played at 6-foot-6, 290 pounds.I think we have players all across the board that have the instinct for that defense, Lett said. DeMarcus Ware, Jay Ratliff, Jason Hatcher, Sean Lissemore I think all our guys can adapt and play this 4-3 scheme. Theyre fast, theyre quick, theyre big, theyre athletic, and thats what you need.Lett was retained as assistant defensive line coach, and hell get a chance to work with respected NFL veteran Rod Marinelli, who is now in charge of the Cowboys defensive line.We just have to get them to adjust to a different technique, Lett said. In a 3-4 scheme, you were a little bit more two-gap, head-up. Were going to get them to shade on the shoulder and penetrate and get up field. So Ive been talking to Coach Marinelli about that, and were looking forward to retraining the guys in that scheme.Lett said it was the focus on penetrating into the backfield that made the position fun for him when he played.Some guys just love to play the 3-4, head up, but the 4-3 is more about a penetrating, we-get-to-eat-first type of deal. Thats what were calling it. Were at the front of the food chain.-- Carlos MendezGo to our Cowboys Corner blog to read Tony Romo's talent "a double-edged sword"