There are a lot of reasons to be excited about the Dallas Cowboys defensive line this year. DeMarcus Lawrence had a breakout season last year. He’s been tagged and is playing in his second straight contract year. Tyrone Crawford provides a solid veteran presence on the other side. Second-year edge rusher Taco Charlton is showing good growth so far in camp. He’s hungry. And raw but talented Randy Gregory will be making his return to football after a lengthy hiatus. Even rookie Dorance Armstrong is wreaking havoc against second- and third-team offensive linemen in training camp.